The game is a bait and switch. I followed the directions faithfully, and said that the ambulance was breaking the rule. But then it seemed to lower my score. Turns out I wasn't supposed to follow the rule, I was supposed to guess how others would follow the rule. That should have been clear from the instructions.
1. The majority said the ambulance was a vehicle, so agreeing with that wouldn't lower your score
2. It's an agreement score, not an achievement score. All it does is measure how many questions you agreed with the majority on. The score does not convey a value or judge your actions, it's just there to inform you how closely you align to others' answers.