Also, anything more than a basic grocer would still want real people to help people with purchasing etc.
I mean, this is a great example against your point (imo). Those self checkout stands, sure they do employ a staffer to monitor, but each of those stands is basically a line that doesn't have to be employed by a dedicated staffer.
They managed to potentially drastically reduce the number of required staffers via self checkouts. I say potentially, because 1 self checkout doesn't inherently equal one checkout clerk, but you get where i'm going with this.
If my safeway can fire the 6 clerks i regularly see staffing the checkout lines, and hire 1 to monitor.. that's still a drastic layoff.
And what about all the manual labor involved? I'm sure it won't be all robots stocking shelves, so mostly stockers can remain employed for the time being, but i'm sure at least a few employees who specialize in managing stock will be laid off as well.
Just because it's not 100% layoff doesn't mean it's any less serious, imo. We're slowly decreasing the available job market simply put. Where are these people going to go?
If we get rid of all the manual labor that humans do, why wouldn't we move the advice-givers to remote offices and improve their utilization? A call center to tell you where the milk is or which wine goes with your recipe might sound bad, but consider that you'd never wait another second to talk to a clerk, and everything would get even cheaper as more and more of the basic questions for the call center get moved onto intelligent bots.
Secondly, once people get used to shopping at stores where they don't have to line up to pay, the new experience will become expected by consumers.
So there is a double effect whereby stores who adopt the new tech will save money on payroll, and stores that don't will lose some business.