Many things are covered in graffiti in Western Europe. It always baffles me that people are in such a defeated state of mind that graffiti is just simply accepted and seemingly nothing is done about it.
There, we have at least one delta now.
Another difference is that one of them is intentionally designed to capture my attention, usually while I'm driving, to try and get me to fork over my money. So that's another delta.
I don't love graffiti, but I do hate outdoor advertisements.
As usual, the answer is found by examining assumptions: 1) It's somehow bad, and 2) People strongly want it removed. (And by accepting those two assumptions as true, and it's also true that the street art remains, that argument infers despair.)
I and many people don't think it's Bad (avoiding a specific definition, an endless discussion). I don't mean it's always Good or never Bad, but generally IMHO it ranges from easily ignored to decent to some really inspiring stuff.
And I find it generally inspiring that some kids have the spirit, creativity, initiative, and determination to do it; to express themselves and not be suppressed by society. Adults have so much agency; it's great to see kids seize some, and in a harmless way (they aren't injuring people, risking anything, etc.). I see the suppression of graffiti as telling kids to be 'seen and not heard'. People embrace billionaires who break rules and then kill and impovrish on a mass scale; all these kids are doing is painting something.
I'd almost advocate that kids have free reign to paint public property (that would seem to get out of control, and any announced limit may be an invitation to break it). It's their city too, and adults should have to live with what the kids have to say. (Still - how could that work? Any undecorated or unfinished surface?)
I understand you may not agree; we need to find a balance.
I obviously don’t have a solution to this, but it’s hard to argue how spray painting is net good even for kids.
Why don’t you call it what it is: destruction of public property?
You may see it differently, but what you see isn't "what it is", it's just your perspective.