The main deterrent is knowing the police are in an area. Otherwise it falls into the category of being anywhere, so why not commit crime x here?
I live in a relatively small town and know how many police officers are on duty at one time. If I know where all those police offices are I also know where they are not.
Sorry but your "scenario" misses a huge piece. People do not go to jail for having beer spilled on their shirt. If the police can not prove alcohol over the limit in the person's body they do not go to jail.
You're innocent? Prove it.
It is called a breathalyzer/blood test that the police will perform.
You also completely missed the point that even if someone gets tracked an pulled over the general public was not privy to the exact location of that person.
Finally, do you realize the manpower needed to put that chain of events together? Sorry but a DWI charge is not enough to justify that amount of manpower to any police force.