I don't think anyone assumed it was a school-sanctioned trip. I know that I wrote that it was a school tradition, and wasn't it? There are plenty of school traditions that aren't necessarily school-sanctioned.

I would say more of a community tradition, but sure. I say it is not a school tradition because it was always only graduates, and the school was careful to have nothing to do with the trips, or even acknowledge them.

Trust me, people did assume it was school sanctioned in the beginning, partially because of the media and their propensity to lean towards the scandal and not the facts. It caused quite a stink.