Rail a natural monopoly, in theory would be no benefit to privatization of the rail. In practice may be get better management and also it creates a political shield for prices which are still in effect set by the state, and makes pay and conditions of workers less political.
The rail companies have to apply government political vote buying type discriminatory discounts ( not even based on ability to pay) , can get millionaires at certain age etc. that can travel at peak times below a true demand management fair. This creates more congestion and a less efficient use of trains than if train companies set fairs themselves. The government insist on discounts, for their favour groups, I think armed forces also get a special deal, government also insist the rail companies through contract allows some people to use the service for free.
In respect to quality of management government does not do as much open recruitment on merit generally, also government does not fire management on merit. Government management would generally be regarded as poor lacking commercial skills. (some people may say).
If in theory government could runs trains as well and wages non-political then would be cheaper for the government to run. There is duplication of back office, rolling stock not used efficiently caused by being privatised and of course profit taken (although the government inefficiency in practice may waste more than the cost of profit). In theory rail privatisation is less efficient, in practice probably not because political nature of employment management, and political nature of fairs creates a buffer as government can blame the rail companies even when their hands are often tied in effect.
If government could run things well then would not make sense to have privatised as a natural monopoly there could be efficiency saving in theory of being government owned, the united states AmTrack is government owned.
Like Royal mail sale tend to think these decisions are made on a political interest rather than utility basis.
The Royal mail sale some free cash to typically middle class that could buy in at fire sale price, one way bet against the public as a whole.
Think this often happens state assets sold below cost to buy votes, from council houses to British telecom.
Where a small amount of money is taken from everyone as a whole in the fire sales of assets, yet a concentrated amount given to a smaller number of people who benefit so cost society a whole, but buys votes from winners, as a small in number so get large amount of money in comparisons to everyone one else who loses a small amount, overall worse for society but can buy votes the story of many government transfers. Take a little from everyone so they dont notice and give it to smaller number of interest groups so that do.
Not quite sure why the rail was privatized poltical reasons weaken unions, to borrow money in effect, by getting companies to invest and then have more money taken out than would be otherwise over longer period to pay for this investiment by giving generous enough contracts to afford this don’t know.