Public transport in Europe is often in a sorry state, but trust me, it's nothing compared to the US. Here in France, a lot of regional trains are very unreliable at best but at least high speed trains on dedicated tracks are fine (very expensive, but ok).
I don't remember UK rail to be a shitshow and/or that expensive but my only experience is going to/from central London to/from neighboring counties and it was fine.
But in the US, oh boy. About 15 years ago I was living with some roommates in Campbell, CA and we went to SF one day. 1h drive mostly on shitty concrete motorways, including probably around $5 of gas. They were heading north for a romantic getaway so I went back to Campbell by myself. It took almost 4 fuckin hours, on maybe 4 or 5 different private companies, and cost me like $25 to get back.
Public transit in the US is so fucked up im almost convinced it's by design.