I also find overly courteous drivers to be dangerous, particularly when they ignore right of way.
There was a crossroad I had to go through daily that often had a long line of cars waiting because it crossed the offramp joining a major highway and a motorway. You would get idiots stopping to let cars go and actually causing accidents behind them because they caused the offramp to quickly congest out onto the highway.
It got so frequently bad that an enterprising local stuck their own Do No Stop cardboard sign there.
In a queue, you can appeal to the emotions of a clerk, attendent, or some other agent with power. Further, if no power agent exists or is sporadic enough that they virtually don't exist (like, say, police on the same roadway you describe) then the action of calling out devolves to simple game theory in which the best mode of action is to simply not participate.
I challenge you to change your mindset:
>take advantage of 2-second gaps
that 2-second gap is simply a buffer. when buffers are filled do we call it 'being taken advantage of' or do we simply empty the buffer and continue our routine?
I always wonder how people like that act outside vehicles. It's really no different to jumping a queue, but I bet of you did that to them outside a metal box they would call you out.