Well a couple of points that often get overlooked.
The USD is very strong right now. The euro hasn’t been around very long.
Compared to the pound in the last 50 years the pound has halved in value to the USD. Mid 80s yes pound hit a low against the dollar then it strengthened again. I remember when I went to NYC around 2007 it was $2 to £1. $500k salary “only” £250k here back then. BA top scales around that now.
Hard to compare like for like. Pint of beer in NYC now is around $14. London around £7 in a pub.
And yeah health care in US can wipe out $100k. Even with insurance it often doesn’t cover the full lot.
Another point I believe is a bigger influence is size and infrastructure.
Rail network is non existent. When I looked at going from SFO to LA. It’s around a 6hr drive. Train was double that or fly for $30 in 1 hour and they are every 30 mins. No brainer.
Yes airlines compete against each other but that’s in.
Certainly in France I have taken the train over long distances and not much difference in time compared to flying once you factor in airport faffing.