Messed up, group of 30 could have something to do with it but should be no excuse. There really is no excuse if you have a list, and can count. These people got really lucky to be picked up.
I have a questions, what did you mean by how is this STILL happening? Were there other stories?
Also, I bet this leads to not only proper sanctions and precautions put in place, but they will use this as a opportunity to flex their might and go way way way beyond what is necessary. Weekly inspections, 1 instructor per 2 tourists, ect... (Of course i'm making that part up but you know what I mean.)