I just want to highlight Undue Medical Debt[0], the NGO that helped implement this.
They have a fascinating model -- they can buy the right to collect medical debts for pennies on the dollar. That debt would normally be bought by debt-collection companies. But once Undue Medical Debt buys a person's debt, they just... forgive it.
This means they can retire someone's $5,000 debt for a cost in the low hundreds. That might be life-changing for a poor family.