You CAn book seats on the train........ in fact for cheap fares you HAVE to book a seat
I am aware of the money stolen by tax-avaoidance schemes but
1. in general those who have the cash, have the cash to pay people who are a damn sight clever than any government and they can (and will) always be a step ahead of that game
2. any extra cash will not necessarily be spent on airports but on fripperies such as defence, old people, the NHS and even roads