The intention of a pictogram is to make clear, at one mere glance, that what people must do or can expect. In that way the sanction for illegal parking is a car being towed away. As a warning to people, this sanction is realised by way of a simple design. Such a defined pictogram mutates over the course of time (due to new car models, etc) and differs in detail by country. The resulting image is above all dependent on the professionalism of the one who it applies. When you come up against the pictograms individually, it may not be immediately obvious. But you understand what is meant. (So it works.) When viewing the different incarnations of a specific pictogram, you notice how it has mutated.
