However cohesive and coherent a system is, it doesn't mean it is better or works well. I have only heard bad things about British Rail. We could nationalise the system at massive cost and it could end up absolutely awful.
I think it will fail either way because no matter how many billions the politicians promise, politicians are politicians and not railway operators. I can only look at who will be running it and know with absolute certainty as to how bad it will be.
Would you put Jeremy Corbyn or John Mcdonnell in charge of a nuclear reactor? This is precisely however what these soviet-esque dinosaurs would do because their purpose isn't nationalisation to make our lives better, their purpose is absolute state control.
State control to them is far more important than you getting to work on time.