I don't know if you are quoting that from a guide, make the schedule at your store and actually see they are equal, or are just guessing or just repeating what you've been told.As a whole payroll shouldn’t go down. Just allocated differently. The problem is, being a new process, and people learning it, stuff takes longer to do at first until people become proficient. Also, time is spent training and teaching the process. So at least initially, it does feel like there’s less hours. Also, it will take some time for stores to figure out how to allocate everything so the most gets done.
I'll give you an example why you are wrong. Before modernization: I was the signing person. I didn't get 40 hours a week, but I got between 10 and 16. After modernization: 0 hours. I don't see anyone doing signing because those hours were kept. No one to do overheads. No one to break down the pallets.
My old pptl, now the gm2 tl, is trying to get some hours for me to breakdown the incoming pallets and sort it between areas. Also time to do overheads.