Why wouldn't Harry ever have had butterbeer before?

Question

In Goblet of Fire we find butterbeer available to students in Hogwarts several times:

At the party after Harry's name is picked out of the goblet:

Harry couldn’t get away; whenever he tried to sidle over to the staircase up to the dormitories, the crowd around him closed ranks, forcing another butterbeer on him, stuffing crisps and peanuts into his hands....

At the party after the First Task:

Sure enough, when they entered the Gryffindor common room it exploded with cheers and yells again. There were mountains of cakes and flagons of pumpkin juice and butterbeer on every surface;

At the Yule Ball:

“How’s it going?” Harry asked Ron, sitting down and opening a bottle of butterbeer.

-

Krum had just arrived at their table clutching two butterbeers.

Throughout the remainder of the series we find butterbeer at many parties in Gryffindor Tower. Even if Hogwarts doesn't officially serve it (except perhaps at special occasions like the Yule Ball), it is obviously not very hard to come by (probably just go to the kitchens and ask for some). It is referred to as "black-market butterbeers" by the planning of the end of exams party in Order of the Phoenix but that doesn't seem to have made it difficult to procure.

This being the case, why in Prisoner of Azkaban was Lupin so sure that Harry would have never tried butterbeer before just because he couldn't go to Hogsmeade?

“I have complete confidence in you,” said Lupin, smiling. “Here — you’ve earned a drink — something from the Three Broomsticks. You won’t have tried it before — ”

He pulled two bottles out of his briefcase.

“Butterbeer!” said Harry, without thinking. “Yeah, I like that stuff!”

Lupin raised an eyebrow.

“Oh — Ron and Hermione brought me some back from Hogsmeade,” Harry lied quickly.

Wouldn't it be very plausible and believable that Harry had once had butterbeer in Hogwarts? Indeed, Lupin of all people would know how easy it is to raid the kitchens, having been best friends with James Potter who routinely did so, as mentioned in Philosopher's Stone:

“Ah — your father happened to leave it in my possession, and I thought you might like it.” Dumbledore’s eyes twinkled. “Useful things ... your father used it mainly for sneaking off to the kitchens to steal food when he was here.”

Lest anyone suggest that butterbeer in Hogwarts only started in Goblet of Fire, we already find it at a party in Prisoner of Azkaban after the Quidditch match against Ravenclaw:

Fred and George Weasley disappeared for a couple of hours and returned with armfuls of bottles of butterbeer, pumpkin fizz, and several bags full of Honeydukes sweets.

---

I am assuming that the butterbeer at parties comes from within Hogwarts, not from Hogsmeade. I am assuming this because it seems entirely implausible that Fred and George are going illegally to the Three Broomsticks when anyone there can see that they are students, and especially in Prisoner of Azkaban when Hogsmeade is under dementor patrol after sundown. Moreover it would be nearly impossible to carry enough back for the entire Gryffindor house, even if they didn't have to go through a "very narrow, low, earthy passageway" that takes ages to get through and then climb up a stone slide. Not to mention that Fred and George would have no reason to pay for the entire house's food and drinks, even if they could afford it (which they certainly can't). As Fred explicitly states in Order of the Phoenix regarding the 25 butterbeers at the first DA meeting:

“Cheers,” said Fred, handing them out. “Cough up, everyone, I haven’t got enough gold for all of these...”

Additionally, it is clear from several passages in Goblet of Fire that the parties are sourced from the kitchens:

“Well, we’d better get downstairs for your surprise party, Harry — Fred and George should have nicked enough food from the kitchens by now.”

-

Hermione took a jam tart. Then she said, “Did you get all this from the kitchens, Fred?”

“Yep,” said Fred, grinning at her. He put on a high- pitched squeak and imitated a house-elf. “ ‘Anything we can get you, sir, anything at all!’ They’re dead helpful ... get me a roast ox if I said I was peckish.”

-

“You know what?” said Ron, once he, Hermione, and Harry had left the kitchens behind and were climbing the steps into the entrance hall again. “All these years I’ve been really impressed with Fred and George, nicking food from the kitchens — well, it’s not exactly difficult, is it? They can’t wait to give it away!”

Answer 1

I think we can take it that Lupin just casually assumed that since butterbeer isn't served at Hogwarts and is generally obtained from Hogsmeade and since Harry wasn't allowed to go there (which was kind of a big deal), he wouldn't have tried it before.

When Harry blurts out that he's tried it, Lupin raises an eyebrow. Having aided and abetted Harry's father, Lupin gets a little suspicious, a little interested, but he seems broadly satisfied with Harry's explanation.

'I have complete confidence in you,' said Lupin, smiling. 'Here - you've earned a drink. Something from the Three Broomsticks, you won't have tried it before -'

He pulled two bottles out of his briefcase.

'Butterbeer!' said Harry, without thinking. 'Yeah, I like that stuff!'

Lupin raised an eyebrow.

'Oh - Ron and Hermione brought me some back from Hogsmeade,' Harry lied quickly.

'I see,' said Lupin, though he still looked slightly suspicious.

Harry Potter and the Prisoner of Azkaban - p.182 - Bloomsbury - Chapter 12, The Patronus

I understand that his suspicions weren't completely squashed, but students probably aren't really supposed/expected to be throwing all night parties with alcohol brought in from outside and I'm not really surprised that Lupin wouldn't exactly have expected students to be giving their own butterbeer to first- or second-years, even if one of them is the boy who lived. So while I agree you've spotted what is probably the result of butterbeer being introduced later in the series and then used more and more, as Himarm says, it's not really such a gaping hole in the story. Lupin quite understandably assumes that Harry wouldn't have had a chance to try something that you generally get in Hogsmeade. In fact he probably got it into his mind that he was giving Harry a special treat, so he's very much going into this conversation with that idea in his head. He is then thrown. His casual assumption has been proven false. He is suspicious when he finds out Harry has tried it, knowing what his father used to get up to and knowing about the existence of the Marauder's Map. He is then pacified by the plausible explanation that somebody else gave it to Harry and doesn't seem to find that so weird. I would agree you would have a point if Lupin had responded along the lines of "What? Students can't bring butterbeer into Hogwarts! You've been sneaking into Hogsmeade, haven't you? Turn out your pockets!" But you ask

Wouldn't it be very plausible and believable that Harry had once had butterbeer in Hogwarts?

And the answer is yes it would be very plausible and believable and Lupin does buy it, essentially. I know he "still looked slightly suspicious", but I think that would likely have more to do with Harry and his body language and what Lupin might have picked up in his voice than any large author oversight.

Answer 2

Butterbeer was introduced in year 3 .

Harry wasn't allowed to go to Hogsmeade in his 3rd year due to the threat of Sirius Black. Sirius Black being the primary threat/villain of the 3rd book, that drove the plot.

‘Well, third-years at Hogwarts are allowed to visit Hogsmeade, but my aunt and uncle didn’t sign the permission form. D’you think you could?

Fudge was looking uncomfortable. ‘Ah,’ he said. ‘No. No, I’m very sorry, Harry, but as I’m not your parent or guardian –’

Butterbeer was a plot item introduced in year 3 to coincide with visits to Hogsmeade. With Harry not allowed to go, it was an item Ron and Hermione could brag to Harry about having and him not knowing what it was due to his lack of being at Hogsmeade.

With the introduction of the Marauders map the acquisition of butterbeer became a non-issue, and so from that point on in the series, butterbeer became readily available to the Gryffindors.

So while Fred and George could have gotten butterbeer before Harry's 3rd year, the fact that it wasn't invented out of universe till the 3rd year, for a plot prop, is why it was probably that Harry would have never had butterbeer before.

Answer 3

We know the Dursleys didn't give him butterbeer so he couldn't have had it until his first year. I would think that butterbeer was like soda in the Muggle world: not exactly healthy and not welcome at the dinner table. So Harry would not have had it during meals. No big events (that included food) happened until his fourth year. By then he had tasted it in Hogsmeade. And the first times he had it inside Hogwarts was:

a. with Lupin
b. during the "we won the Quidditch Cup" party

These weren't everyday things. It was not readily available to 1st and 2nd years.