In many parts of the world most cars are equipped with a device known as a Hazard Light.
There is this switch located inside the car, which is usually in an easy-to-reach-place from the driver's side but is simultaneously hidden in such a way as to take several minutes and a glance at the Owner's Manual to discover. The switch usually has a serious looking triangle on it, allegedly making it easier to find.
When this switch is pressed or pulled, all of the exterior lights on the car blink. This is in itself fascinating, but not the limit of what this button can accomplish.
It appears that when one's hazard lights are on, one is able to do anything without fear of reprisal. The original purpose of hazard lights was to warn other drivers that the car was stationary because it has broken down and won't go any further.
However, over the years the hazard light's purposes have been extended. Nowadays, leaving one's hazard lights on means you can park anywhere - there may not be anything particularly wrong with the car in question. Leaving hazard lights on while parked on a double yellow line or in front of a fire hydrant means that the driver has just nipped into a nearby shop. Or if you see a driver who has pulled over to the side of a busy road and has stuck on their hazard lights they may be lighting a cigarette while holding a hot coffee in the other hand, or perusing a street map.
It is rare to see a hazard-lit car exceeding the speed limit. Often they crawl along at a snail's pace when everyone behind it wants to go at 70 miles an hour.
A similarly related phenomenon is drivers who turned onto the motorway a while ago but neglected to turn off their left turn signal, thus making you wonder if it's safe to overtake or if they're going to get into another lane and get out of your way.