Dealing with thousands of grievances over the years, as compared to someone that doesn't even work OT, I'd say yes.
Another difference between the IAM and the TWU, which would influence the equalization is the fact that on the TWU, if there is a bypass the Member receives the pay without having to work the hours. With a system like that, equalization is even more important. In a system of bypass where the Member that is bypassed is offered to work the hours ahead of someone else, then equalization has less of a need.
Of course, those that see these issues as a matter of someone begin greedy and should be penalized for it, would see this issue in a manner that projects self interest.