Many, many years ago, public services and government-controlled monopoly companies had a mission to provide a service, not to make a profit.
Then, privatization was "the thing" to do and politicians were frothing at the mouth about estimated profits. Everyone with 2 working brain cells already had the "too good to be true" feeling, but since we all know politicians, they went through with it.
Other then others I don't think that private or public ownership is the deciding factor, but whether your focus is service or profit.
For Europe, the result is higher prices with massively reduced quality in the areas of postal services, trains, energy and several others. It appears to have worked so-so (i.e. no drastic negative changes) for public transport (busses, underground, etc.) and it actually does appear to have worked in telecommunications.
The rage right now is buying these things back. I would love to make a final calculation at the end, about what this whole stupidity has cost the taxpayer, in other words: How much money was transferred from the public to some private companies. And then sue the fuckers for it and jail them. I just fear that won't happen.