I can give you one very specific answer in that my late father decades ago worked in IT for a collections agency and one way that biz works is they pay a fixed amount to buy some companies 120+ day accounts receivable file (the feds and every state highly regulates this and its highly variable and complicated, but this is the simplified version...) and this gave them a vast pile of records and legal ability to collect the debt. Now obviously they got most of their revenue by annoying the heck out of debtors right up to the legal limit. But they're leaving money on the table if they don't resell all the data they can legally sell. So sure, even 20+ years ago collections agencies were uploading records to various data aggregators in exchange for a check. Not just the original debt but followup activity and intel WRT the collections process. I would imagine that's only increased over the last couple decades. Most of these data transfers were two way streets, not simple data for money trade, and obviously they maximized profits by leaning the hardest on the people most likely to actually pay up, they did not waste time on debtors known to other collections agencies as hopeless deadbeats.