Like I mentioned in another thread, it’s very frustrating when you want to taxi out from the [wherever] and find two airport vehicles parked in the taxiway, having a smoke and flaffing around about something, or playing on their smartphones. And there appears to be no way to honk your horn at them.
Right now, the only resolution seems to be to run them over. . . . 
I have a funny anecdote about that - and talk about realism!
I was flying in some new aircraft, (forgot which one), and I TOTALLY borked the landing beyond all recognition - ended up all over the place and ultimately drove on the grass to - eventually - reach the ramp area leaving a trail of busted signage and markers behind me.
Next thing I know there are two or three airport vehicles racing towards me - presumably to give me a thorough chewing-out for my abysmal airmanship and to get a credit-card number to pay for the signs, lights, and markers I ran over! 