Every campus safe-ride I've heard of is free for all students no matter what. The issue here is the breathalyzer, not that they provide free rides for the drunk ones. At the college I went to, for example, you could use saferide as long as you had a campus id (now you can even use it without as long as you are with a group of <5 with an id among you, or if you pay $2). There's no incentive to get drunk there, because the ride will be there regardless. Since Uber is breathalyzing the clients, it's actually in your favor to be over the limit, hence the extra liability.