It's a simple thing to do. Even if the trainer is hauling 30 kids, it only takes one second to check that strap so that is only a few minutes of actual checking time even if we add the time it takes to walk between the horses while checking. We have been seeing more and more helmet use at dude and guest ranches. The principle that seems to work best is to put helmets on the staff. If the wranglers wear helmets the guests won't complain about wearing them.
Reports are that although it takes a bit of effort to get it started it works quite well.