You’re right it’s not cheap. Under Giuliani, it costed NYC $3 billion annually for their police force of 37,000 souls.
Removing 15% for administration leaves a force of about 31,500 officers at four shifts means at any time about 7800 police are available to patrol 300 sqare miles.
That leaves an officer density of 26 per square mile on any one shift at an annual personnel cost of $2.1 million/mile.
Shouldn’t the citizens of NYC rightly expected crime to have been diminished?
The job was a bit more complicated than hiring cops.