Yeah, this is a mostly American hyper correction. You see the same thing with "an herb". I'm guessing it's a relic from people who spoke French affecting the same pronunciation in English. You occasionally even see "an history"

May well be a regionalism an well. I say an herb and don't pronounce the H. But a hotel (or a history) and do pronounce the H--and hence use "a." There are a number of words that can go either way because the (acceptable) pronunciation covers both variations.

In US English, I've only ever seen 'a history', but I have seen 'an historian'. I'm really not sure why.

"historian" is a fairly long word. If you stop to create a word break, and then aspirate heavily on the "h", it can be uncomfortable to say. If you don't, then the "h" can get very soft if people try to say the whole word quickly and I imagine that some people drop the "h" entirely because of that, or make the "h" so soft it feels natural to contract

Interesting. As I said - my view is from the UK - I should have put 'often' or 'sometimes' before it (although I was taught 'an hotel' at school).

As a southern Englishman, i would say, and expect to hear, "a hotel". I associate "an hotel" with Northerners, Cockneys and speakers of Estuary English, and perhaps also posh people (although maybe that's Northerners or Cockneys trying to be posh, in the mode of Hyacinth Bucket).

I was taught 'an hotel' in Scotland by a very old-fashioned teacher. She could, of course, have just been plain wrong and I've been carrying this with me for decades repeating the mistake. Checking the UK newspaper style guides they seem to all insist on 'a hotel'.

"an hotel" is just wrong in my experience, which I think is where "people trying to sound posh" comes into it.

The south and the "posh" (there is quite some overlap there as there is a perception that the south is more posh and the north more rough) use "a hotel" which is also technically correct, as you move north the "h" gets dropped so "an" becomes correct, though if you are writing that you should have a apostrophe to indicate the dropped letter (an 'otel) - in fact the 'postrophe is sometimes even pronounced by way of a very small pause (this is often a clue when decided if someone has a particular accent or is just imitating it).