Student loans are mostly prohibitively expensive at market rate when bankruptcy is allowed.
Look how many students don’t pay up and are generally an expensive hassle to track down. Those rates on guaranteed loans are still way below what they’d be on such an open market.
This applies for people with or without collateral ~ which is making all the arguments related to collateral look specious in the extreme (as if they weren't already).
Tracking down debtors can be a problem in a country that doesn't even care to track down illegal alien serial killers ~ I can see where you're coming from on that ~ but eventually they trip up and the internet reveals their presence in some manner.
I think it's just a case of lenders not caring to pay the top dollar to the best track and trace folks. They imagine they can get by for cheap ~ maybe spin off that job to some call center in India or something (not to sound cynical, but isn't that what they do these days?)