[@Ariamis]I won't stop one of your characters from asking IC, but here's the basic principle:

The sacrifice rules were not added as regulations, so they didn't need to be enforced at all. In fact, the temp rule (which was added as a regulation) prevented the hospital staff from enforcing the sacrifice rules (not regulations), as anyone cooperating wasn't interfering with the hospital staff, who are the only people the carnage sisters/ Monokuma can attack.

If that didn't clear it up, I'll explain it better IC when someone asks.