Those yellow school buses from the movies are everywhere!
Windows that only open straight up (and not in/out)
Cities where streets follow a grid. And almost all streets allow cars. As a European I'm accustomed to look for the city center; a place where there are no cars, where streets are meandering, where there are terraces to sit outside and have a coffee. A place that's amenable to walking, to hanging out and enjoying the atmosphere. I did not find such a space in the american cities I've been to. And it prevented me from enjoying the place.
Riding a bike is dangerous and an enterprise, not a mindless means of transport.
Working people are afraid of medical bills.
Catching the bus seems to be an activity reserved exclusively for disabled and poor people.
The surbuban parking lots! Yeah everyone's heard of them, but nothing will prepare you for the overwhelming size and quantity
The importance of team sports in American schools is surprising. My friends' children were involved in football, wrestling (unheard of in British schools), football, basketball, baseball ... with coaches for all those sports and a massive amount of parental involvement.
The lack of pedestrians. A couple of weeks ago I got off the bus in Worthington, OH and walked about a mile up High St and then down some residential streets back to a friend's house and I did not see another pedestrian - this was at 5pm on a weekday, on a street with wide, wide sidewalks. When I told my friend where I'd walked from, she was truly shocked. She thought I was weird to get the bus downtown in the first place because only poor people take buses
American drivers are far more likely to stop and let a pedestrian cross the road, even when there is no marked crossing. Possibly due to the novelty of seeing someone on foot.
Unless you live in a big metro area, if you don't drive or at least have a car, you'll be hard put to get food or other necessities
The huge amount of text-based road signs we have in the U.S. Every mile or so you're barraged with information about the speed limit, the next exit, the name or route number of the road you're on, and other miscellaneous information. In the UK you can drive for miles with no signs at all, and when you do see them they're likely to just be symbols of some sort.
Walking across the road in the wrong place can be a crime.
Stores have their own parking lot and you cannot run errands in medium towns without driving between different shops.
Lawyers have much more cultural cachet than in almost any other country. The idea that lawyers are on a par with doctors as far as people with high-class occupations. Note the perennial appeal of law school, or of lawyer shows on television. Also, a majority of elected officials have at least graduated from law school, whether or not they actually practiced as a lawyer for any significant amount of time. (Compare this to the number of engineers in power in China.)
Power lines above ground.
People look at you weirdly if you tell them you walk to work.