Thankfully, there is regulation in this area for any school that gets state funding. If state-subsidized 4-years don't accept X number of transfer students from that state's community colleges every year, they can say goodbye to a chunk of their state funding.

I can't speak for private universities, however.

Oh, they'll accept them. They just won't count towards your major. They're sneaky like that.

That might run them into hot water with the accreditation folks.