I don’t understand why people do it.
As you (maybe) can see in the second photo, we have a security camera looking directly out at the sidewalk at all times. This camera records constantly, so we technically could go looking for the special artists who decided to turn our red building into something more colorful.
But really, it’s not worth our time to do that: we just have someone paint over the graffiti.
In the end, what’s the point? You can’t write legibly, the graffiti is up for less than a day, and honestly, it’s not memorable when it happens many times a month. What a pointless exercise in futility.