Part of the European system is that you are admitted to a certain college and only to study a certain subject.

I got into my college ('university') to study computer science, and I had interview and tests to check aptitude for that specific subject, but I wouldn't have been admitted to study something like medicine or music instead as I wouldn't have had the aptitude for that.

When you go to college in the US does one of the departments have to say 'yes this person had aptitude for our major'? Is it possible to get into a college and then realise you don't have aptitude for any of the majors?