If this is like what I saw in Maine coastal tourist towns this summer I suspect its popular with Europeans because the $15.10/hour local wage is attractive. But more so it's because you get to spend time a few months in a beautiful location surrounded by other attractive young people. Party scene is probably great.
I suspect you're correct on that front, too. I have family in an area that has been bringing in European teens to work seasonal tourist-facing jobs for probably(?) decades now. I can't speak to how they are treated outside my view, but anecdotally, they seem to really enjoy the opportunity. They get their little euro-crew together and basically have a College experience.
Locals like them, too - they're charming, generally well-behaved, polite, and it doesn't hurt that they don't have to pay them very much. I like to think the cultural exchange between the Europeans and the otherwise isolated locals is fantastic for broadening horizons, also.