Actually, many of those countries don't have systems similar to Medicare for All. Netherlands, supposedly second in this list, has a mostly privatized system with mandatory insurance, so does Switzerland. France and Germany have semi-public and private health insurance companies. The US has bigger (and different) problems than merely the existence of health insurance companies.
Hapankaali
Where I'm from there has been a minimum income guarantee since 1965. In fact, the constitution says the government should ensure every resident has sufficient income to live. A single-person household with someone who is permanently unemployed receives about $1500 per month (you receive additional money per child). This is the lowest income a legal resident is allowed to have. Every rich European country has a similar system, though most opt to cover rent for the poorest, and give a smaller amount for the remaining expenses.
It turns out that willingness to work isn't an issue, because most people don't actually like to do nothing. The employment rate is far higher than in the US.
Actually, we're not a long way off from that. Hydrogen production facilities utilizing (excess) renewable electricity output are under construction as we speak. For example, a large project in Kazakhstan (which has large stretches of windy, sunny and empty steppes) is aiming to be online in 2030 with 30 GW of production going towards green hydrogen.
The Wlz (which replaced the AWBZ) covers only a minority of total health care costs. Expenses were €29 bln in 2023. "Mostly privatized" is accurate.
Both the Netherlands and Switzerland have universal health care systems and negligible rates of lack of insurance. My point is just that private health insurance isn't the (only) problem, as these counterexamples show.