I’m always amused by this. The US has a hugely diverse set of attitudes to things and yet a surprising number of people there then look at a more populated combination of more than 25 countries with varied languages and histories who have fought many wars over history against each other have some singular approach to parties or cycling or anything else.

we have different culutures but Americans also have decades of media exposure to inform them on what an "American party" is. Especially if you grew up in the late 80's/90's where "party" was a literal genere of movie to subscribe to.

Now of course, media doesn't reflect reality. But it can certainly homogenize sentiment.