@sattut! This:
" may have more severe ethnic quotas "
is simply wrong- and illegal.
Where are you from, that this is your belief of American universities?
Also, your logic is off: the people who can afford to send their children to St Andrews will be able to send them to “smaller elite colleges” that “tend to have students from wealthy and classy backgrounds”. They go to St Andrews to have a foreign adventure, because they are anglophiles, lots of reasons. That the handsome prince went there means they have heard of it, and yes it seems glamorous.