Determining professor tenure via student rating is obviously an extreme idea and likely to fail as outlined by many of the other comments in this thread. But,

Determining professor tenure via student rating is obviously an extreme idea and likely to fail as outlined by many of the other comments in this thread. But, framing students as customers, is a worthwhile debate to have in the US given the high cost of tuition. Considering the crushing debt student loans can create, students should think of going to college as an investment with risk and return. I wish it were not this way. Let's not pretend that most US universities aren't operating like sophisticated businesses concerned with marketing, generating revenue, and besting competitors. That makes students (along with some other groups) customers. And perhaps if these customers are unhappy, maybe we should blame management (administrators) instead of professors.