Talking about sackings or resignations is completely OTT, the school's error was having an over simple scheme which didn't allow for the possibly inevitable unusual event and not seeing it at the time.

That sort of thing happens in one way or another quite often, when my kids were at school it was decided one year that the limited tickets for a school trip would be allocated on a first come first served basis on a particular morning, it didn't sink in to them that those children using the school bus would have no chance against those living within walking distance and who could get there early.