I think there are bigger things to worry about. I would just tut and be done with it.
Don’t forget starting an engine once stopped isn’t without energy cost. Rough rule of thumb is the engine needs to be stopped for greater than 30 seconds to be worth it versus the energy cost of replenishing the battery. Then of course, the greater wear on the starter motor and battery etc.
Typical of modern thinking, yes its a waste of energy but stopping idling isn’t going to solve anything at all. Certainly not worth worrying about.
Whereas the atmospheric conditions at platform 1-4 at St Pancras International well that has to exceed Euro legislation every single day. its horrible but its not the evil motorist so its fine.