I agree with your basic position, but most definitions of the word violence that I could find included the notion of: destroying things with intent to intimidate through fear of harm, threats such as brandishing weapons, and so on. It's not as simple as 'you didn't touch me so you didn't do violence' - and it makes sense when you consider the case of robbery at gunpoint.
That being said - the destruction of flock cameras is in no way violence. No one sees that and takes it as a threat of harm - at least no one acting in an honest way.
Isn't that the difference between a threat of violence as opposed to violence? Which is directly adjacent and thus treated similarly by the law.
Brandishing a gun at someone is a threat that you'll shoot them but, importantly, is not the same thing as actually making good on the threat. (From the victim's perspective the distinction is rather important.)