I passed my test in 1986 so thought I'd give the theory test a go on YouTube to see how I would fare - that's when I found this mistake (although I guess it was the YouTuber's mistake as its not the official DVSA stuff, but I assume the questions are valid/similar to the official ones)
If the questions are the same/similar, then many of them are common sense I would say, but also many of them are those things a sensible, courteous driver would normally do, however I agree with itsaminithing that these days there are plenty of people who drive like complete @rseholes either because they seem to think they have more right to be on the road than you or they are so dumb they don't know or care how bad their driving is.
I have made mistakes driving (I guess most people have even if they don't like to admit it) but hopefully I have managed to convey my apologies to the other driver when I have cocked-up. In those cases, many of the folks from my comment above just don't give a sh!t, or as mentioned, they are so dumb they don't even realise how bad they have driven
From the link provided by xrocketengineer - I don't know if that is an exhaustive list of all US signs - if so, I note the US signs don't appear to have very many "prohibitive" (or as they are called "regulatory") signs and can't see one for "No overtaking" - maybe it's not a thing in the US?