simply isn't the deal nearly all of them signed.
We all have a moral obligation to fulfill our part of contracts we sign ... in a non-recourse real estate loan, that moral obligation is satisfied when the borrower signs the deed over to the bank. It's a negotiated and agreed upon resolution that is acceptable to both parties.
Bank aren't benevolent creatures who would never take advantage of a borrower. What if they hire an appraiser who they know will write a garbage appraisal so that the loan/sale pencils. What if they approve a loan application that they know puts the borrower in significant jeopardy of default etc.