The premiums returned to workers are the small wedge of the pie. The bigger portion is the total cost of health care for those workers, their families, and all the new participants, all of which will have to be funded by a new government source. Currently we spend in the order of $1.6 trillion dollars in the private sector of health care, most of which goes for medical services and drugs. This tab will have to be paid by the government under a Medicare for all system, and while they can no doubt bargain and jawbone that figure down some it still will have to be paid.
The beauty of the payroll tax is that it can be progressive. For higher wage workers, those with the $20 k, $30 k, $40 k premium costs, they can pay the highest rate and still come out ahead, for those workers with no employer based plans, they can pay a far lower rate and still contribute. I’m adamantly opposed to selling ANYTHING as “free”. NOTHING is free, and we could spend half of our GDP on medical care desires and still not drain the existing demand.
As much as possible, people should pay their own bills, including the cost of their medical treatment and their catastrophic protection. I always have, and I have never been close to high income, though I have built small businesses, trained and employed craftsmen, produced much real wealth.