The TGV in France makes a profit. As does the Shinkansen in Japan. Intercity routes in the UK aren't high speed but are all profitable. Rural rail lines are not profitable and commuter lines are about break-even, depending on the fares charged. E.g. the tube in London is break even as it receives no operating subsidy, but it's quite expensive compared to e.g. the Paris / Madrid / Berlin metros. If you want to lubricate congestion in your city an easy way to do it is to encourage people to take a more space efficient form of transport by subsidising this. As a business proposition it probably makes sense for the overall region in the same way that it makes sense for a factory to move stuff around on conveyer belts rather than having everyone carry stuff from one station to the next. Britain has low productivity compared to the western EU average. It is posited that one of the big reasons for this is that our infrastructure is a bit shit.