Does American private insurance pay for everything? And if you say "but they can pay out of pocket", well Canadians can come to America and pay out of pocket too.

No.

For a lot of people it very much doesn’t. And the cost is very prohibitive for people getting any care at all when insurance doesn’t cover it, so they end up not getting necessary care and then ending up on disability for life.

A healthy population *makes money for taxes and buying things*, too.