Why were there no protective enchantments around the tent, when the trio was caught by Snatchers?

Question

Here is what happened in the Deathly Hallows, just after Harry accidentally mentioned "Voldemort".

"The name's Taboo!" Ron bellowed, leaping to his feet as a loud crack sounded outside the tent. "I told you, Harry, I told you, we can't say it anymore. We've got to put the protection back around us quickly. It's how they find "

But Ron stopped talking, and Harry knew why. The Sneakoscope on the table had lit up and begun to spin; they could hear voices coming nearer and nearer: rough, excited voices.

And once Harry, Ron and Hermione are captured, the Snatchers and Greyback search the tent and take possession of the sword of Gryffindor.

"Hey!" came a shout from inside the tent. "Look at this. Greyback!"

A dark figure came bustling toward them, and Harry saw a glint of silver to the light of their wands. They had found Gryffindor's sword.

Given that this happened while they were comfortably settled in one place, having a conversation, after listening to an episode of "Potterwatch", and given how careful they had been up to then about security, it strikes to me as very odd that they had no protective enchantments in place at this point.

Does anyone else find it unrealistic, that the one time they are lax about security, Harry accidentally fell for the Taboo? Or is there any other explanation for this? Do the protective enchantments break once the Taboo comes into play, and was Ron pointing out that now that the enchantments must have broken, they had to redo the spells quickly before the Snatchers got there?

Answer 1

Using You-Know-Who's name breaks all protective enchantments and allows the speaker to be tracked.

‘You and Hermione have stopped saying You-Know-Who’s name!’

‘Oh, yeah. Well, it’s just a bad habit we’ve slipped into,’ said Harry. ‘But I haven’t got a problem calling him V—’

‘NO!’ roared Ron, causing Harry to jump into the hedge and Hermione (nose buried in a book at the tent entrance) to scowl over at them. ‘Sorry,’ said Ron, wrenching Harry back out of the brambles, ‘but the name’s been jinxed, Harry, that’s how they track people! Using his name breaks protective enchantments, it causes some kind of magical disturbance – it’s how they found us in Tottenham Court Road!’

‘Because we used his name?’

‘Exactly! You’ve got to give them credit, it makes sense. It was only people who were serious about standing up to him, like Dumbledore, who ever dared use it. Now they’ve put a Taboo on it, anyone who says it is trackable – quick and easy way to find Order members! They nearly got Kingsley –’
_{Deathly Hallows - Chapter 20: Xenophilius Lovegood}

^{(emphasis mine)}

In the quote you provided, they had the enchantments up, Harry said You-Know-Who's name, the enchantments broke, and the Death Eaters apparated to their location. That's why Ron said they had to put the protection back up.

Answer 2

They did use protective enchantments, but they were broken due to the Taboo.

They did use protective enchantments. Harry reminds himself of this when he gets nervous about some noises he heard outside their tent.

“He remembered the sound of a cloak slithering over dead leaves many years ago, and at once thought he heard it again before mentally shaking himself. Their protective enchantments had worked for weeks; why should they break now?” _{^{- Harry Potter and the Deathly Hallows, Chapter 19 (The Silver Doe)}}

There were protective enchantments around the tent, but once Harry said the Dark Lord's name, they all automatically broke and became useless. That's why Ron was saying they needed to put them back quickly.

“The name’s Taboo!’ Ron bellowed, leaping to his feet as a loud crack sounded outside the tent. ‘I told you, Harry, I told you, we can’t say it any more – we’ve got to put the protection back around us – quickly – it’s how they find –” _{^{- Harry Potter and the Deathly Hallows, Chapter 22 (The Deathly Hallows)}}

Ron knew that saying the name would cause their protective enchantments to break, which is why he kept trying to stop Harry from saying it. This also proves that the Taboo would have succeeded at breaking the protections, as well.

“NO!’ roared Ron, causing Harry to jump into the hedge and Hermione (nose buried in a book at the tent entrance) to scowl over at them. ‘Sorry,’ said Ron, wrenching Harry back out of the brambles, ‘but the name’s been jinxed, Harry, that’s how they track people! Using his name breaks protective enchantments, it causes some kind of magical disturbance – it’s how they found us in Tottenham Court Road!’

‘Because we used his name?’

‘Exactly!’_{^{- Harry Potter and the Deathly Hallows, Chapter 20 (Xenophilius Lovegood)}}

The Death Eaters knew that only people who were actively fighting the Dark Lord would dare to use his name, so they used this to track them.

“You know who used to like using the Dark Lord’s name, Weasley?’ growled Greyback. ‘The Order of the Phoenix. Mean anything to you?’

‘Doh.’

‘Well, they don’t show the Dark Lord proper respect, so the name’s been Tabooed. A few Order members have been tracked that way. We’ll see. Bind them up with the other two prisoners!” _{^{- Harry Potter and the Deathly Hallows, Chapter 23 (Malfoy Manor)}}