Construction site discrimination was rampant when I was a welder back in the 70s, but we were exempt, anonymous, just as Zorro, The Lone Ranger, Batman or Ned Kelly, because one can't weld and wear a helmet.
The rank n file wore orangee yellow hat, the electricians were blue etc.
I remember being one a job, where there was a question team from each of the trades, including the labourers, even management, (white helmets)
A tie breaker question between the yellows and blues, was, Which English King had 6 wives?
I was the question master (not enough welders on the job for a team)
Charlie Kelly was the head of the Yellow Helmets, the team conferred, but Charlie's answer left me in no doubt that he got an oblique peak at the answer on my desk.