I'd like to imagine that ancient cultures had an elaborate visionary sense of humor. Sitting around the campfire, they devised the most intriguing practical joke on archaeologists.
Very common in Russia also, the vans usually put the number of the official route on the window, so you'd know exactly the route that's going to be taken. Wish they had this Sydney, but the government is anal on taxing and regulating people. So no micro businesses for Sydney :(