Re: But public money...
At the time the railways were being privatised I was one of their victims AKA commuter. It struck me then that it was being done in a completely arse-about-face manner unlikely to improve my daily life. There was no reason at all to suppose that the infra-structure company would have any reason to align its plans, or lack thereof, with the requirements of the operating companies. Regional franchises removed scope for competition and the length of those franchises tended to inhibit all but the most essential investment.
The result was the same, largely ageing, hardware being operated but the same staff with, for the most part the same management with even less alignment between customer need and service provision.
It would have made sense to sell off whole lines, infra-structure & operations as a whole. It would have made sense to keep infra-structure separate but to allow multiple operating companies to run competing services over them. It would have made even more sense to have done the latter but split the infra-structure into regional companies so as to concentrate each management's attention on getting its own bit right.