You're thinking too small and too focused. Costs in technology come down, technological improvements happen rapidly, processor and storage capacity grow exponentially.
For the moment, it may not be feasible to have drones everywhere, but there's no reason it cannot or will not be feasible in the near-term future.
5 years ago there were no Quadrocopters, 5 years from now I'm sure there will be sufficient technological development for mid-sized drones, tiny "hummingbird" drones, and massive fighter-replacement drones.
Facial recognition software, camera technology, all of that gets better yearly. Compare the first GoPro to the HERO 3D and consider what can be done in a very short amount of time.
And while drones need to report to operators, technology will allow a single operator to monitor multiple drones which are effectively autonomous or semi-autonomous until overridden by the operator.
So, costs will drop as you replace on-patrol officers and cars with fleets of drones that can summon response teams from a smaller overall pool of officers.
So, the issue isn't the technology, nor the cost of operators, those things can both be easily solved and both are ancillary to the core issue of Rights and Freedoms and the idea that we, as Americans, are entitled to those rights that protect our freedom from undue scrutiny.
You're saying "we can't do this right now" and I'm saying that you're missing the point.
As we take steps that erode our rights there's nothing to prevent the inevitable erosion of Privacy writ large as whatever technological limits there are now will soon be overcome.