Hi,
I have heard by many that a unique quality of uPenn is the ability to take courses across all schools. But can’t you do that at other universities as well? For example, Duke and Northwestern have a similar policy.
That’s not really unique. Many universities offer that. Case Western is one; University of Richmond (where I go) has a similar policy, although it’s not completely open (I believe most of the leadership classes require you to be in the leadership school).
Some schools are in consortium with other area schools that all students to cross-register. Each consortium has its own unique features and the distance from your home school to other schools is a factor as well.