Someone very close to me has over 1 million fucking dollars in medical debt from emergent and intensive care. She wasn't abusing the ER; she had a sudden catastrophic illness and nearly died. Aint nobody suing or garnishing her wages. Actually I think it might be wiped by now, as so many years have passed. She also had an extended stay in a rehabilitation hospital which added on a few hundred thousand more. Again, no lawsuits and no wage garnishing.
99.9% of the time it's not worth it to these institutions to sue people who can't or won't pay. They just get the government to pick up the tab, either through Medicaid or as a tax writeoff. They can also sell the debt to a third party.
Medical debt is not dischargeable in bankruptcy, in most situations.