In 40 years I'd expect most of these minimum wage jobs to have disappeared so it wouldn't really matter.

Right now in some cities, Amazon and other services will deliver your food. I'd expect this to gain popularity as delivery costs come down and the cost of running an Amazon warehouse type grocery store would be significantly cheaper than running a traditional grocery store. This will drive down prices and will eventually run traditional stores out of business. So you're left with an automated warehouse moving your food around and a self driving car to deliver it. Shouldn't need that over prices clerk after all.

Of course, you'll still need some workers, but if their jobs are still needed after mass automation, they're probably already worth a lot more than minimum wage.