I worked at National Power during the and after the privatisation process. The difference between the old CEGB staffers and new intake was chalk and cheese. Ever have someone get up in the middle of a meeting and say they are going home because it is 4 o'clock?
But I'm convinced it is due to management style and expectation setting, as those with a bit of nouse quickly adapted to the new hardware / software / regime and made a success of their careers. (Those that didn't were offered eye wateringly good redundancy packages until the die hard refusniks who thought they were untouchable were given compulsory redundancy on MUCH reduced terms.) New management gave the department focus and goals, which we achieved through hard work and the ones who went with the change enjoyed the new ethos tremendously. The old CEGB management were side-lined and moved on ASAP as part of privatisation.
Nationalised companies can work and do work in many countries. You need dynamic managers to lead these organisations so they compete with the private sector. Being good at what you do and efficient while doing it will make a nationalised enterprise unattractive to private investors as there is little to no fat to trim off for profit.