You are right! As we are in Europe we fill like this will be less of an issue than in the US.

Nevertheless, we will soon test what happened when we shout our flying HyLighters.

For a different perspective; I suspect they'd be fine in the US. Signs and drones are different. The former is petty vandalism, so is the latter sometimes but others you might feel pretty justified in removing the little spy camera from your space.

But a blimp, high up and clearly doing something? Nah, it'd be fine.

There are open questions around the limits of airspace below the FAA ceiling and property lines. There's been multiple cases in the US of people intentionally shooting down drones operating above their property, including in urban areas, and it has not yet been heard by the Supreme Court. Common Law held that property owners controlled their property from the Earth to the Heavens, which is inclusive of airspace. The current law in the US says that property owners control their airspace within their "reasonable control".

I am not a lawyer, but is is a very open question if you're flying low enough someone can visually sight you and shoot you down over their property, whether or not that this is a violation of the law /for unmanned vehicles/. Drones in particular have become a serious nuisance and many property owners have taken actions against them in the US triggering court cases, most of which haven't yet reached their conclusion.

EDIT to add that the rules here even vary by state in the US, in some states you own 83 feet over your property of airspace, in others it could be as much as 400 feet (above 400 feet is controlled airspace under the jurisdiction of the FAA). Generally speaking, shooting any aircraft, jamming any radio signal, or shining laser pointers on any aircraft is already federally illegal in the US and violates FAA/FCC regulations, but it's not clear that these regulations are actually constitutional and enforceable, or that it cannot be an act of self-defense to shoot down a low-flying aircraft intruding on your property.

> Unfortunately it is also exceedingly likely that the folks who shoot at road signs as their particular outrage against government are most likely to think that surveillance drones are there to spy on them, and not inspect infrastructure.

I think you're conflating issues. At least where I grew up, people didn't shoot road signs out of anger at the government. They did it out of boredom. Sometimes as a competition with friends, sometimes alone. I never partook myself.