it’s not that we don’t like them - but more that they’re more winter/holiday focused (speaking generally), and usually roasted rather than fried.
But also, Brussels are on the menu everywhere (edit: where i am) in the US. middle of July, at a bar, get a side of Brussels. I don’t think Brussels are served commonly at Sunday lunch year round in the uk.
What region if you don’t mind me asking. I’ve lived in a couple of US states on the west coast and I’ve never encountered Brussel sprouts so casually and definitely never fried. It’s usually in a part of a dinner at a ‘nice’ sit down restaurant and always roasted in the oven.
Where in the U.S.? Lots of people hate them. In fact, I’ve never seen a side of Brussels sprouts just given to you as a side. Maybe it’s an option, but there are always other options.