Earlier quoted context omitted.
Was that "union rules" or "the way the company had agreed to comply with their agreement with the union"? Because 'work to rule' can be a double-edged sword, and in my experience companies just love to blame their own chosen behavior on the union. "We have to fire you if you're late five times this quarter, because the union" really means "after we frequently and arbitrarily abused employees under the excuse of 'atte…
That's still "union rules". If the union chose to be pedantic and insisted upon these rules in negotiation, then it's really the union's fault.
It's a bit like the tax code or some complicated piece of bureaucracy. Some of the stuff in there sure seems stupid but you can bet it was put in for a reason that, at the time at least, looked sensible. In the case of things like "only an electrician is allowed to do that", it's a pretty safe bet that at some point in the past management tried to do an end run around the agreement and have cheaper labor do something they weren't trained or compensated for. In the US at least the system is so adversarial you end up with hard lines being drawn on both sides.