Why Did Dudley Have to Have His Piggy Tail Surgically Removed?

Question

Why did Dudley have to have his piggy tail surgically removed? Why wasn't the Accidental Magic Reversal Squad dispatched to remove the tail and modify the Dursleys' memories?

After Uncle Vernon insults Dumbledore one too many a time, Hagrid retaliates by giving Dudley a piggy tail:

He brought the umbrella swishing down through the air to point at Dudley – there was a flash of violet light, a sound like a firecracker, a sharp squeal and next second, Dudley was dancing on the spot with his hands clasped over his fat bottom, howling in pain. When he turned his back on them, Harry saw a curly pig’s tail poking through a hole in his trousers.

[...]

‘Shouldn’ta lost me temper,’ [Hagrid] said ruefully, ‘but it didn’t work anyway. Meant ter turn him into a pig, but I suppose he was so much like a pig anyway there wasn’t much left ter do.’

_{Philosopher's Stone - page 48 - Bloomsbury - chapter 4, The Keeper of the Keys}

So Hagrid's magic didn't work right. Dudley subsequently has to have the pig's tail surgically removed in a Muggle hospital:

‘All right, we’ll take you to King’s Cross. We’re going up to London tomorrow anyway, or I wouldn’t bother.’

‘Why are you going to London?’ Harry asked, trying to keep things friendly.

‘Taking Dudley to hospital,’ growled Uncle Vernon. ‘Got to have that ruddy tail removed before he goes to Smeltings.’

_{Philosopher's Stone - page 68 - Bloomsbury - chapter 6, The Journey from Platform Nine and Three-Quarters}

First, Hagrid is barred from using magic at all. Second, to knowingly use magic in a Muggle-inhabited area, or in front of a Muggle, violates section 13 of the International Confederation of Warlocks’ Statute of Secrecy (OotP - chapter 8, The Hearing). Third, when Harry produces a Patronus in front of Dudley during the Dementor attack in Order of the Phoenix, he immediately receives a letter from Mafalda Hopkirk advising him that he has been expelled from Hogwarts and that he will need to appear for a disciplinary hearing at the Ministry.

How did Hagrid get away with using magic in front of Muggles, and not have been brought up on charges of breeching the International Statute of Secrecy? Since he meant to turn Dudley into a pig, but only managed a piggy tail, does that constitute "accidental" magic? Why didn't the Accidental Magic Reversal Squad show up, magically remove Dudley's tail and modify all three of the Dursleys' memories like they did when Harry accidentally inflated Aunt Marge¹?

★ I do not prefer any answers from the HP Wikia or the Wikipedia.

¹_{Technically, Aunt Marge was the only Dursley to have her memory modified. The Accidental Magic Reversal Squad left Vernon, Petunia, and Dudley alone.}

Answer 1

Hagrid was old enough that he no longer had "the trace" on him so the Ministry no longer could monitor his magic activity. Initially I thought "but what about Harry's trace?" but Harry hadn't started school yet and I seem to recall that due to that he didn't have the trace put on him yet.

So the answer simply seems to be that the ministry never knew that Dudley had a tail magic'd onto him and Hagrid didn't seem to feel the need to inform them.

Answer 2

Hagrid's wand isn't registered under the ministry, technically he shouldn't have a wand because it was broken from being expelled after he "killed" Myrtle. So whatever magic Hagrid uses is strictly his own.

Answer 3

This is something that I believe is simply a mistake in the books. That being said we can hypothesize an excuse for this...

Since Harry is still technically underage, he cannot get in trouble for magic he does unintentionally since he doesn't have a wand (turning his teacher's wig blue, vanishing glass, shrinking sweater, growing back his hair, flying to get onto the school roof, etc.). This is important because the ministry can track this magic, but only use it for acceptance into Hogwarts, not punishment. On the other hand, Hagrid is "of age" and is therefore does not have the trace, so the ministry can't track his magic either, which is shown multiple times (Riddle murdering his father/grandparents, Ron confounding the examiner for the diver's test). The only conclusion is that neither Hagrid or Harry had a trace on them at this point that could be used for discipline and therefore the ministry had no knowledge of Dudley's Tail.

That being said, it still doesn't account for JKR's blatant disregard for the ministry ignoring some spell-work done in the Dursley home. They do cite Harry for the magic Dobby does in COS, the magic Harry does in OoTP, and acknowledge the magic he does to Aunt Marge in PoA. That being said they also ignore the magic that Arthur does when he, Fred, George, and Ron pick up Harry prior to the Quidditch World Cup (blasting out the fire place, repairing it, lighting a fire, and shrinking Dudley's tongue), Dumbledore's magic when he picks Harry up (glasses of beverage, couch moving, etc.), and the magic that Tonks does while packing Harry's trunk. Note, all of these were not in front of the Dursleys but the fact remains that Harry still had the trace. I think that at this point we, as readers, must accept that there is no way that JKR could have avoided some of these situations and that the Dursley home is an exception to the rule in some cases.

Answer 4

I think that the Dursleys did not want to get into more magic, so they wanted to have it removed not by magic. There also is a chance that Mr. and Mrs. Dursley did not want to spare too much time on it, so that they wanted to get the tail out before he got to school. Add these together and it makes quite a bit of sense.

Answer 5

It's because Dumbeldore gave permission to Hagrid to use magic to fetch Harry, Hagrid mentions when they were getting back from the hut and he suggested that he use magic to speed the boat to get back faster.

Answer 6

It's because the Dursleys, being related to Lily through Petunia, were allowed to know of magic. Harry living with them, being a wizard, only cemented this. The warning letters he got from the Ministry after this event were most likely just jerks trying to make trouble for the famous Boy-Who-Lived.

Answer 7

Because a Hagrid was expelled, and the trace breaks when the student is expelled from Hogwarts and when they turn of the age of 17 or Hagrid was using one of his relatives wand that he asked to be made into an umbrella and therefore, he used a different wand, instead of his own broken wand, because, remember chamber of secrets when Ron broke his wand and was told by professor mcgonagall that his (ron's wand need replacing) ? Because the spells backfired onto ron, remember when he tried to curse malfoy to "eat slugs" and ended up cursing himself. That is the other reason why and how the ministry didn't know of it. And another thing. They were relatives of a wizard so they were allowed to see magic and not be adhered to the strict wizard world law of not knowing about magic. And, well, since Hagrid asked Harry to keep it a secret between them as well. in the movie so I would assume Harry kept that thing a secret. So now ya know.