It’s somewhat in the credit agencies best interests to ignore or heavily discount medical debt. Because so many people have it, and not by choice, to destroy everybody’s credit rating because of medical debt would decimate a significant portion of the country’s ability to get credit. That would have a domino effect on a great many things, and cause enough of an issue that it’s likely there would be further regulations on the credit agencies.
Remember, businesses want customers, they just want customers they can trust to pay the debt. Credit agencies using medical debt to decimate an otherwise decent credit rating denies those businesses a perfectly trustworthy customer.
They absolutely should be regulated more, though, regardless of how they handle medical debt now. Frankly I think a great step would be if we extended HIPAA laws so that the credit agencies literally cannot receive any information about medical debt whatsoever.