I was thinking about it - trying to figure out. what is really going wrong here .. in terms of preventable things that can be done.

First off, there's no doubt that a LOT more people are going into these canyons. It is attracting a lot of people, including people with a wide range of experience.

One of the big problems ... basically you need to rappel down into the mouth of the canyon. Once people finish the rappel, and pull the rope down - they are completely at the mercy of the canyon and the weather. It can be very tough to get out again. There are few places where the canyon walls are climbable.

Also, communication with the outside world is nonexistent inside the canyon. So there's no way to get weather updates when you are underway .. no way to even see approaching thunderstorms until they are on top of you.

Overall - it can be a pretty risky set of circumstances.

ONE Positive Idea did occur to me.
If these canyoneering groups designate a couple of people as "standby rescuers" ... then their chances of survival are improved. For example, you've got a group of 7 people. Five people get the opportunity to explore the canyon, and rappel down. But two people remain on high ground, with extra ropes and gear for placing anchors. The two people on top follow the progress of the group below, but they stay on the rim. If anything goes wrong, they lower ropes to the group in the canyon. Then so long as all the exploring party has ascenders (for rope climbing) - they have an opportunity to escape the canyon if need be. It's not a foolproof system, but it's better than what people are doing now.

cheers,
dT