I believe it's not done like that, because there is little opportunity to make huge profit on such privatisation. Would you rather own the entire rail network, or buy some trains and have to pay rent for rail access? No one will invest in the latter without financial history of operations in such environment.

To do privatisation properly the state should breaker up the infrastructure from the services. Split the services into separate companies (then do we want them to compete or each will have it's niche? Usually it's the latter). Restructure and run those service companies until they're profitable. Finally sell them, or better yet over the span of the years get the employees to get a sizable ownership share, give local go another sizable share, sell the rest on the stock market.

That IMO is roughly a good way privatisation could work, but it takes more than one electoral cycle to do it right, and which government wants to create gifts for their opponents? So we usually don't see anything like it.