I've seen one that seemed to be an exception to the rule. It was an RV covered mostly in anti-Congress, anti-corperation, anti-vax, anti-Isreal, anti-China, anti-Russia, and anti-CIA stuff. It called out several notable politicians from both sides as well as the entirety of the CIA for being pedophiles. There was a complete and surprising lack of culture war stuff and a couple equally surprising mentions of the war on drugs being bullshit. No racism that I noticed, no flags or symbols, and no direct mention of the police or military. It was parked near a stop sign on my way to work for several weeks and I feel like I noticed something new and confusing about it every time I drove by.

My best guess is that the owner doesn't vote at all.