I used to work tradeshows for General Motors. Many of those rules are requirements by fire marshals. Those requirements were paid for by dead bodies and burned buildings. Auto shows are a lot safer since all the batteries are disconnected and fuel tanks emptied.

Examples: cars on deck short out due to salt water spray:

https://imgur.com/rn1zEEt

Long video with examples of car carrier ships catching fire:

https://www.youtube.com/watch?v=Y8ewh8zdGkc