If only it were that simple. As it is, we already have people stealing / ripping up political signs of the politicians that they don't support. These typically end up in a dumpster, river, or tossed in the woods somewhere. Now all they'd do is save the signs until after the election and then put them back out. Can you imagine how many voters stole or vandalized Mills or Lepage signs? Now imagine what those same people would do if they knew that they could cause financial harm to someone simply by putting those signs back up in the middle of the night, as opposed to just trashing them. How would you go about proving by preponderance of the evidence who the responsible party is? It would be a nightmare.

Additionally, in order to make this a law or even a city ordinance, you need the politicians to sign off on it. How many do you think are willing to pass a law or ordinance that specifically targets them and only them?

Source: I got stuck dealing with these theft and criminal mischief cases every political season when the politicians would complain about someone destroying their signs.