Joe,
You are somewhat correct about licensure. IATSE electricians are not required to be licensed IBEW electricians, but certainly can be. This is why there are some convention spaces here in Las Vegas will only use IBEW electricians to drop power to a client on the floor and then the IATSE or client people will then simply plug it in and turn on the switch.
I would say that the majority of IATSE electricians are qualified personnel, but are qualified for the scope of work that they encounter on a daily basis. Depending on the electrician they would be quite familiar with the NEC articles 518 to 540 which deal specifically with the industry.
Another thing to remember is that the products that are listed for use by these electricians are designed to be of a "Extra Heavy Duty Type" and isn't installed for very long of a time. The infrastructure and permanent equipment and wiring is still being installed by IBEW electricians. The temporary products are generally used as per the manufacturers instructions and according to the NEC.
As indicated by this picture, though, there are some unqualified people out there using equipment and wiring methods not allowed in particular applications. There are also those who have almost no clue what they're doing (i.e. non-electricians). I believe that this is apparent, in different degrees, in any industry. The ESTA Certification is attempting to help shrink this hole. I think all of us here take great pride in making our work neat, clean, and safe, but there are those "electricians" out there who don't as we have seen in a few of the photos here.
Qualified and Licensed are unfortunately not synonomous.
