ULEZ cameras are also run by private contractors: Capita and Yunex. Is the entire objection centered around the distinction between owning vs. operating? i.e. if each city owned their network and used it (as ULEZ cameras are - in addition to their primary reason) for policing and used contractors to operate it then the objections would disappear? I see, I didn't realize this was a question of structuring of the purchase orders.
It's another thing entirely if a private oligarch owns the cameras.
Flock and ULEZ are not the same.