Okay, that's fair.
It would also be reasonable to say that some of those operational costs, if they have to do with labour, would be recouped by the government through income tax payments. You don't have to comment. I can tell you that I think it's all reasonable that if you receive a paycheque, this occurs.
The other significant portion is...the police also have a responsibility not only to protect the lives, safety, and property of citizens, but they also have a duty to protect the lives, safety, and property of people who are acting as either lawful demonstrators or, quite frankly, even as hooligans, and you're responsible for the safety of the people you arrest.