I've started thinking about acceptable practices for traffic cops. This line of thought was likely triggered, by the Motorhomediaries' crew and their run in with the Jones county, MS thugs in blue. Anyway, I came to the conclusion the only good reason for stopping anyone in a vehicle would be that they are causing grave danger (or impediment) to everyone else on the road.
So, consider that you own a road. It's your private property. You want to make money by allowing people to use it in order to get from point A to point B. Any time you or your agents pull a driver over you slow down travel to nil for the client you've just pulled over, and you slow down the rest of the drivers too. This means, per unit of time, there are less people getting from point A to point B than there otherwise would have been without if you had just let the guy with unreadable tags go through. You'd only want to pull people over in order to avoid a wreck or blockage on the road that would slow people down even more than the act of pulling a driver over.
Needless to say, your clients would have accepted such a possibility before using your road. In fact, many would have no problem accepting more traffic management. I'm not trying to guess some magical ideal; I'm trying to figure out what the road-owner would slowly learn over time. For instance- dead people don't generate repeat business. I suspect handcuffs and pepper spray would tend to lower one's customer base too.