If you own 100 houses and you lose one you still have 99 houses. If you sold it at a loss because it was costing you too much to keep then you made a smart decision.
The bank takes the knock,carries on as if it's business as usual in an effort to prop up their own revenue.
Too big to fail I guess.
The bank also has rights on the property after it goes into default. They don't lose all their money.