I think that the Post Office fiasco shows us all that no-one is ever responsible, privatised or not.

The worst part about privatisation is the level of “who, me?” that happens.
Huge corp doing bad? Fining an entire org takes forever (if it even gets there), and every shitty cog just does their small bit of arseholery, while pretending they’re not the problem.
And the C-levels mostly walk away with a slap on the wrist, if any.
A revolving door of executives, making small parts of the awful changes each.