National Industries will always be slow to change and expensive to run, Private industries will always be trying to save as much money for their shareholders as possible.
Railtrack themselves went cap-in-hand to the government on, I think 4 occasions, and they gave them money from the Lottery fund, of all things, that which was supposed to only go to charity.
The fact of the matter was that the Rail system was being drained from the top, till almost none filtered down to the actual Track maintenance. This will always be a problem in a Private enterprise. The managers want the money, that, after all, is what they went into business for, not the joy of management.
At least whilst the higher-ranks are under Governmental pay-scales, they know that they cannot simply grab a huge slice of pie and abandon the sinking ship, which is what Railtrack did.