here is a question.
what incentive will there be for the poor with a hangnail and old who are lonely to stay out of the ER?
There's no incentive now. What Medicare doesn't cover, the hospital writes off. (Oh, and Medicare reimbursement is usually about 65% of the normal bill...or less. It's better than no payment, but hospitals lose money on a lot of treatments.)
If all healthcare was paid through Medicare, a lot of things would have to change. Private rooms? Nope, everyone on wards and pray that infections don't spread. CAT and MRI? Nope, we'll zap a couple X-rays and send you home. You want a TV, and meals? You better be ready to pay out-of-pocket. It'll take us back to the conditions 100 years ago.