To answer your questions:
1)Training someone to handle this task would require a lot of time and assumes that said individual is capable of remembering
and comprehending the necessary proceedures even though they may not have done the task in many weeks/months. And in a production-based environment, said person's focus would not
be on logical troubleshooting and safety, but getting the machine running as fast as possible. This would create the increased risk of fire, electric shock, machine damage and serious injury. In my current line of work (cinema repairs) all projectionist/managers are warned not to reset any breakers on equipment until it can be checked out. Those who have ignored this have suffered the consequences of damaged equipment, total facility outage and loss of job. Finally, some people simply cannot be trained for the task. (Film projectors are very easy to operate, but so many people can't do it.) Would you want the responsibility for the injury or death of a trainee who couldn't hack it?
2)I think OSHA would weigh into the second question. It can be stated as only qualified
individuals should be opening electrical enclosures in a workplace. Machine panels which would be opened for the routine operation and cleaning/operator inspection, sure, as long as it's deenergized and locked out.
Breaker panels, disconnects, transformers, etc. no way. That's why there are electricians. And in the 480 volt class, only a Darwin Award candidate would be nosing around in an enclosure if he's not qualified.
3)True, very true. But would you want a "qualified" plumber to change out a service panel? Or, in my case, I'm qualified to work on cinema projectors and sound systems, and have worked as an electrician as well. Am I qualified to work on the main switchgear in a cinema? Absolutely not. The closest I get is changing a bad breaker in a sub panel serving projection equipment, and only when I can work safely. (That means shutting down the subpanel. And I lockout/tagout.)
The scenario ldlee is asking about is too frought with hazards and would leave his company open to major liability.