SNCF is profitable: https://www.lemonde.fr/en/economy/article/2023/02/24/sncf-re...
Pre-pandemic the main intercity routes were all private operated. The operators had to pay track access charges to cover maintenance costs but they also had to bid to the government to buy the rights to operate the franchise. I.e they had to say how much profit per train service they were willing to pay to the government for the right to operate. The privatised rail sector collapsed because these companies overbid for these rights not because the routes themselves were fundamentally unprofitable.
TFL operating surplus: https://tfl.gov.uk/info-for/media/press-releases/2023/march/...
Japan has never closed a shinkansen route. They have closed many rural branch lines though.
Britain has a low immigration rate compared to Europe. E.g net gain ~750k compared to 1.9m to Germany last year. Germany also has high rates of unemployment for unskilled labour yet they have a sophisticated and highly automated high tech manufacturing economy.
https://en.m.wikipedia.org/wiki/Immigration#/media/File%3ANe...