Strawberry or if they get too ill their insurers can just drop them out. Or if they lose their job the person and family stops being insured, even if one person is on expensive treatment. Then they cant find another insurer who will insure them. appreciate a lot of folks don't have insurance, really. It's a lot more complicated than just 'poor folks'.
Medical bills are the biggest cause of bankruptcy in the US, depending on the source, between 600,000 and 1 million families a year go bankrupt as direct result of med bills. How many have filed for bankruptcy in the UK because of medical bills? Zero. None.