[hannasanarion]

Compulsory purchases are constitutional, as long as Congress can reasonably invoke its taxation power in application of the penalty. Americans are already compelled to buy health insurance, but as of the 2017 Republican tax bill, the penalty for not doing so is $0.

[flexblue]

Then it's not a compulsory purchase, it's a tax. The money doesn't go to the insurer. Even before the penalty was $0, it was too low to be effective.

In Switzerland, it is compulsory to purchase insurance, there's a basic plan that all insurers must offer, and if cost exceeds a certain fraction of the income, the state chips in.