People are awful when they think they aren't being watched, especially with communal or other people's property. It's why things are covered in lame low-effort graffiti tags, why bathroom mirrors have things scratched into them with keys, and why bridges over highways all have metal grates to stop people from throwing rocks at oncoming cars.

When people know they're being watched and there will be immediate consequences if they do something bad, their behavior changes. If they don't, they're awful. We've seen this for decades (arguably millennia, as we know Pompeii had graffiti too)