“The complexity of these cases isn’t a function of the number of people failing to pay their mortgages. “
It is exactly a function of the number of people failing to pay their mortgages, combined with the number of people who want to still live in a house as if they DID pay their mortgage.
Do you think Utah would have ruled in this way if the homes in question were vacated by the former owner - and were standing empty?
If the homes were vacated there would have been no ruling at all -- because there would have been no court case to speak of (at least in terms of a case where two different parties were contesting legal points).