Moose, as usual, is right. I'm sure that's exactly what happened. It was right next to a beach where a canal comes out blind to the swimmers.
I think we invented tubing and that's all we used to do. Figure eights and donuts to get the tubes out of the water and torture the poor sap who was on it. This was before those cheap yellow ones. We used giant tractor tire tubes with the stem that stick out six inches. we would use duct tape to tape on grab handles and to tape a ski rope to the tube.
All we had to worry about back then was running over swans, which seemed to always be funny to the guy driving the boat, or falling off in a weed bed that came to the surface.
Things have changed so much and there are so many people that just don't understand basic boating etiquette let alone rules or laws that we barely go out on the weekends.
I do take my kids tubing and will not stop but, I must tell you, being the driver is not fun anymore. To do it without spotters, we wouldn't even do that back in the tractor tire days. Sad thing is, the dad is going to be found at fault for not having a spotter, regardless of the actions of the other boater (who is experienced).
I was told that both parents are on suicide watch... I think I would be too...