Even a self declared muggle fan like Arthur Weasley barely understands anything. He never thought about reading muggle newspapers, or novels or got to London and watch a play or sit in a cafe or whatever.
It makes no sense.
The consequence of making your whole fictional world revolve around a middle/high school, with the Hogwarts headmaster being much more powerful and historically important than the Minister of Magic, is that said fictional world becomes fundamentally childish and silly. Which leads directly to stuff like the plot of Secrets of Dumbledore, in which the international wizarding leadership election is decided by... a ritual involving a hedgehog.
If they truly loved to serve humans, if that made them truly happy and they saw it as the perfect way of living there'd be no need to magically bind them to a family and forcing them to do their bidding. That this is done is proof that they are indeed enslaved and brainwashed.
Rowling could have just said that the elves working at Hogwarts are fairly paid employees, and left it at that. Making a whole civil rights subplot out of them was a truly baffling and unneeded choice; it'll be... uh, interesting to see what the series makes of it now that "We can't fit that into our movie runtime, sorry!" won't be an excuse for deleting it.

I don't think I realized just how poor the worldbuilding was until JKR posted a magical history of the United States online before the first Fantastic Beasts film. She showed absolutely no understanding of the native peoples, the size of North America, or American history from colonial days onward.
I do feel some sympathy for Rowling here, in that she was in a lose-lose position on this particular issue. Establishing that Britain is the only country in the world with a wizarding society would have been awkward, and invited critical readings of ethnocentrism, but establishing that the world is full of similarly developed magical communities required her to do a lot of culturally sensitive worldbuilding she clearly wasn't interested in, and brought up all sorts of tricky questions as to why such other communities tolerated Voldy's takeover of wizarding Britain - twice. She probably should have just taken the former tack, and accepted the ensuing criticism as the cost of doing business.


