I'm not a lawyer and definitely not a lawyer in "almost everywhere", but it is surely illegal in almost everywhere with western-style property rights? Especially if it left residue after the fact. On the other hand, who is going to take this to court? These are largely one-off tourists who won't have a vested interest in the matter after tomorrow.

People are very possessive about the state of their car's exterior, imagine someone sticking one of these on a high end car.

Also, it sounds to me the area is not actually a "no parking" area - it is at least conceivable the court's interpretation would be different if the claim were true. Residents are painting the curbs themselves.