At some point, we've all been stuck behind a car leaving passengers on the road, a van unloading its goods or more frequently on city streets, a garbage truck.
There's really nothing you can or should do about it other than wait, perhaps raise your voice a notch, or if you're running out of time and patience, call the police if there's problem. Getting out of your vehicle to confront a group of garbage workers, doesn't sound like a good idea and it certainly isn't one in practice…