In short - you can buy a banana for a dime or give the government a nickle and get a "free" banana.
I'm super glad my mom has Medicare! But she isn't benefitting from it being efficient, she's benefitting from it setting the rate it pays and requiring providers to accept it.
The other is a compulsory payment to a government entity as a result of earning income.
The rest of the developed world would very strongly disagree.
The penalty for not making that payment can be death, is likely financial ruin.
For many people, that optional payment is enough to buy a home.
Ask around about "optional"
Then we can set that aside and recognize net, liquid income will go up for most everyone.
All in the US more or less pays roughly 2x or more what some other countries pay for equivalent healthcare, so there is nominally room to extend coverage while keeping costs flat in theory. In practice, it's complicated. Also 'roughly' and 'more or less' have some wiggle room for systemic differences, but it's about right.
How would that be? It seems like it certainly would to me. Maybe by less than employees plus employers currently pay in aggregate healthcare costs, but I can't imagine a way where the government pays for Medicare-for-all and taxes don't go up.
Do you have a specific idea in mind that I'm missing?