I think this might actually work better than giving everyone equal punishments for sibling craziness. If mom knows who started it, the kids are much more likely to fess up from the beginning and not play the “he said/she said” game. Honestly, many people have cameras trained in their hallways now.
This mom just happened to fake them before they became reality. She’s not the only one! When we bought our house, the former owners had a motion detector aimed at their daughter’s door. Really, after watching some of the insane arguments my kids come up with, I can’t blame anyone for trying to mitigate the issues before they start. It’s rough.