I have a few friends who do courier or delivery service on motorcycles. While their practice of illegally parking, or riding on pavements are frowned upon, most of them do not have a choice. Looking at things from their perspective may help in understanding the situation a bit.
They are all given time limits to deliver their stuff, and the system that calculates the estimated time taken doesn't account for things like jams and accidents. So, cut them some slack. Afterall, they are the ones working so you can stay in your homes to eat food that is cooked somewhere else.