I've seen places with separate unions for ordinary workers and for lower- to mid-level management. They have different incentives within the company so it's kin

I've seen places with separate unions for ordinary workers and for lower- to mid-level management. They have different incentives within the company so it's kinda hard to have the shoulder-to-shoulder, but ultimately both are much weaker than upper management and the company as a whole when it comes to negotiating, so it makes sense.