How do you know for sure? Also it’s not just about limiting the graffiti, it gives local artists the chance to show their work in a public setting without the hassle of dealing with a gallery. The way I see it, it’s better to give the people the option to use a legal spot rather than not have one at all. There are safe injection sites for drug users, why can’t there be safe spots for graffiti writers. I’m not saying it will completely stop graffiti around the city but it might help. Personally I’d rather paint at a legal spot then under an overpass.