The most likely outcome in the tow truck case is that they repossess the tow truck and sell it at auction, only losing a small fraction of the money they loaned you. If someone can't afford a truck they borrowed, you still have a truck.

You can't take back someone's education, which is what makes this type of loan intrinsically riskier. Because you can never get rid of student loans, though, they don't have to do any risk analysis or say "no" to any students. They say "sure", no matter what the data says on the ability to repay for the type of degree that you're applying for. Since nobody is denied funding to go to college, colleges have no economic incentive to price degree programs by expected income. The result is that college becomes more expensive and less accessible to everyone.

It's a really bad situation.