Yes, they are. I've been working a booth at a convention showing off some tech and asked a passing worker for an extension cord. The response was that they asked on the radio, but the only person available to perform this role was on lunch so it'd be at least 45 minutes until I could get an extension cord.
I have had this happen in many different situations when working with union members.
Anecdotally, I do not want to be a part of any union that has these types of rules.