Fun fact, the US has always had some of the highest wages in the world- even dating back to colonial times before 1776. Adam Smith did a detailed accounting of them, going occupation-by-occupation and noting that American colonist wages were higher than on the British mainland. (I'm excited because I literally just read this last night. I would link if I could to the specific pages in my book).

I believe the standard explanation is that most of the colonists were British (already a high-wage country at the time), and you really had to pay skilled labor to get them to leave & settle on a new continent. Plus labor mobility between the proto-state governments of the time (Virginia, Massachusetts, etc.)

Mostly because most people have lots of options for employment and they typically don’t take the low options. In a place with nationalised healthcare you would still be paying for it through taxes paid by the labourer but I guess the system would be a bit more progressive than in the US so lower-skill labour would demand a smaller premium for healthcare. Though I think there’s probably more than just labour costs in the US. Eg maybe it is expensive to get the right permits to install fibre optic cables.