In my experience this sort of situation is helpful for business owners who want some sort of enhanced police presence, building owners looking to solve traffic

In my experience this sort of situation is helpful for business owners who want some sort of enhanced police presence, building owners looking to solve traffic problems with their garages and event runners who want some (really) enhanced security. These are all things that even well funded police departments would not really consider. The nice thing about these arrangements is that the person or organization paying for the off duty cops can exercise some control over them.