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.
Not a lawyer either, what I've read about street art in Germany is basically: if it leaves residue (physical changes your object) = property damage, if it's easy to remove without a trace = no case.
Which is why a lot of street artists swapped the can for painted paper and water-soluble glue.
Or, related to cars: hard to remove stickers = property damage, some chalk on the tires or shaving foam on the hood = no case, deal with it.
In BC people have sued the police and won for "property damage" when the police put chalk on their tires, so I'm pretty sure the same would apply for this sticker.
Oh, they switched to harder-to-remove ones at some point, because douchebags tended to remove them and continue following their douchy ways of behaviour.
A hard-to-remove sticker that takes up a third of the windshield is a really great idea IMO; all the "Putinjugend's" issues aside, I think StopXam are doing a great work.
Quite often, recipients of those stickers totally deserve it. I recommend watching some of the videos from the channel 'vermontdevil linked to.
I thought few times about starting something similar in Poland but then I understood StopXam really works only because they're government-backed program, so if someone gets too angry about having half of their windshield covered in a "I don't respect people" stickers, the police will bring him to order quickly.
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.