Except that it isn't UBI for students. It's nothing even remotely similar to UBI. Those students still need to pay for housing and food and everything else. The loans students get aren't just free money in students pockets either. It's just "free money for schools" with extra steps and those schools are happy to take the money and pocket it.
Imagine if we really did just give every 18 year old kid hundreds of thousands of dollars in free money that would never need to be paid back. That'd be a terrible idea for a lot of reasons, but while schools would probably still benefit the most, they'd also have to compete with all the other things those kids could spend that money on and prices likely wouldn't be quite as bad.
It's the opposite of UBI—UBI you're given money that you don't have to pay back. Student loans that you can't default on is money that you can't get out of paying back.
If housing in one place get too expensive you can move to a place with cheaper housing.
You can’t really do the same for colleges. Reputation is not something you can simply manufacture more of.
The comparison is not even remotely valid.