They cannot choose to not live in campus?
They can live outside of campus.
The thing about US Universities is they are one of three major institutions (church and bars are the other two) for young adults to find a mate. Find your future wife or husband while studying and living in the university.
Living in college also provides better networking. One of my friend kids is at studying at Brown University. He is now friends with some of the richest kids in the world. He still in his first year in college and want to start a hedge fund with his rich friends. Lololol
It also allows young adults to experience independent. To figure out what they want in life without their parents guidance. It also to celebrate their youth, ie partying.
College football.
College life.
Top party college.