It's certainly possible to require that if debt collectors demand the courts help them collect their debt, that they have to provide certain pieces of evidence to the court.

This is already the case: in order to convince a court to garnish wages, debt collectors have to prove to the court that the person accused actually owes the debt. They could also be required to provide evidence that the person is wealthy enough to pay.

A person not paying and not being able to reasonably afford to is no crime and should not involve the court at all: the person who made the loan made a mistake. The reason lendors are allowed to charge interest is so that they can asses the risk they will not be able to recover their investment in some cases -- these are those cases.

If someone can pay and chooses not to, that is a matter for the courts, so if a debt collector wishes to have the courts take money from these people they should have to prove they fall into this category.