They definitely have a very hyper-capitalist definition of violence. It's sort of pathetic how much people somehow care about the property of the ruling classes that they will never own.
But imposing your own preferred art on public commons is a (minor) form of violence, in any economic system. Especially when you do so with paints of questionable chemical composition, or with images/text that is likely to offend.
I would also say that doing the same thing even on your own property can be reprehensible, as long as it is visible to the public. Just because you own a house doesn't mean you should be able to make it look however you want on the outside, especially not in ways that are actively unpleasant to those of us that need to walk by it every day: we the public should have a say in how your private property looks. A most anti-capitalist position.
Sometimes councils put up several designs to be voted on by the public, but they will largely follow a bunch of design norms that will be whatever the architecture firms they hired think is trendy, for example.
And how many election programs even talk about artistic taste? That's not why we elect people, and making that an election point would be a distraction from real problems, so why not let society be and if people are more artistic in one area and make more public art, let them make it?
Even beyond electoral politics, many cities have public NGOs and other organizations that seek to shape this sort of thing from an early stage through various legal means (and sometimes even through civil disobedience, like tying themselves to a building to protect it). If they are broadly in line with the tastes of the people, they tend to thrive; if they are not, they will often die out.
And yes, in certain cities and towns, people actually like the way grafitti looks and are bothered when someone goes and whitewashes a beautifully painted wall. That's perfectly fine, and is a part of the culture and esthetics of that place (and here, destroying the art that people enjoy is an act of violence against the public and/or the artist). But it's also perfectly fine for other places to want neat walls with clean textures, and marring their beautiful walls with grafitti would be an act that goes against the public.