[dragonwriter]

> The US has not one but two of the largest single payer health insurance programs in the world.

Neither Medicare as a whole nor Medicaid is single-payer. (Individual state Medicaid plans may be single payer plans, but very often they aren't, either.)

Traditional Medicare is single-payer, but the majority (as of this year) of Medicare beneficiaries use partially-subsidized private insurance (Medicare Advantage) plans, not traditional Medicare.