Other comments already pointed out counter-examples from the UK etc., so let me give you a German one:
The Berlin public transport system was running perfectly fine until it was privatized.
Now the infrastructure is starting to degrade, it's gotten less punctual by objective metrics and it has also gotten much more expensive. The new owners are basically just milking the ever living hell out of it because they know they can.
It's gotten so bad there's now a lot of talk that it should be nationalized again.
The Berlin public transport system was running perfectly fine until it was privatized. Now the infrastructure is starting to degrade, it's gotten less punctual by objective metrics and it has also gotten much more expensive. The new owners are basically just milking the ever living hell out of it because they know they can.
It's gotten so bad there's now a lot of talk that it should be nationalized again.