given how much is a labor costs - I suspect foam might even be more efficient.

also - are those poles set in concrete? I suspect some of those delinquents could just pull the pole out entirely.

A good few of them are set in concrete. I’ve seen posts from someone online called the_guardrail_guy, who goes around and checks the regulations on guardrails making sure they’re not too close to the road or anything. He’s looked directly at multiple flock cameras, and each one he’s recorded himself inspecting has been set in concrete.