Why is there electrical run to the sales racks? You talking in like the lighting section? If they are running pipe down to the shelving from the ceiling and there are pallets stored up there, seems like the problem is a horrible choice of size and/or type of raceway, not with whether or not it has a wire EGC in it.
Never heard of this union = no EGC thing. In any case, I find it unlikely that the electrical contractor of a home Depot is making the decision of using a wire EGC or not, I bet that's already been decided by the engineer who drew up the plans. I've never done a home depot, but I doubt they are "design/build".