Disneyland was, in my experience, very good about helping cast members spot potential danger situations before they arose. This came, primarily, from experienced cast members passing information down to the newbies on the job.
Like you said, placing the proper value on theme park employees is key to the retention of good ones. It's tougher at theme parks that only operate seasonly and thus can only employ part time workers; so the idea of a full time ride operator is a luxury parks like Disneyland have that others do not.
I find it interesting that most ride ops do not secure the restraints to the max. As long as the lap bar is locked and the seat belt, if applicable, fastened, they have done their job. Although it's highly unlikely that anyone will fall out of a ride with the lap bar locked, on occasion I have asked ride ops "Could you possibly push this down a little more?" and they invariably can and will. I feel more comfortable with the lap bar pushed down all the way, even if it means that I can't move.
It wasn't until recently that I discovered that the lap bars on Nitro at Six Flags Great Adventure can be made to fit tightly. I survived over 50 rides on this coaster with the restraints at the minimum snugness necessary to keep riders in their seats. On my last visit, the ride op pushed the lap bar down so that it fit me tightly, without being asked. Later in the day, a completely different ride op also pushed the lap bar all the way down. The beginning of a new trend? If so, it's a good one.
A continuing problem at theme parks is ride ops trying to accommodate guests who are simply too large to safely fit into the restraints. I have watched ride ops, sometimes in pairs, exert as much force as they possibly can in trying to push a lap bar into locking position on people who really don't fit under the lap bar.