You have a VERY WRONG idea of what happens in the US.
In the US it is very much like it is in the UK. Normally, you won't hear a peep during a movie in the US and if you do peep, you may get dirty looks or even asked to leave.
HOWEVER...there are a few movies, especially premiere night in some places, where there is clapping and other items. In some places in the US with some movies there are some that hoot and holler I suppose and it has been getting worse over the years. I was surprised that it is now done with certain movie crowds AFTER the night of the premiere. Not sure what to think about that.
It IS a thing in the UK though, at least recently. Know someone who went to a movie (this one, actually, that the thread is about), and you know what, much to their annoyance, there was clapping and other things going on during the movie. I will say it annoyed them greatly, but there you go.
So...It's not just the US it appears.
Most of the time it is VERY MUCH looked down upon to clap and shout at a cinema in the US during a movie. To think that it is normal to talk and clap during the show in the US is an incorrect assumption and could, depending on the movie and time of it, get you kicked out of the movie itself.