That's certainly true, but then you have to add back in the cost for LEDs, land space, and labor for harvesting. A retailer is going to be required by local laws to pay at least minimum wage, which is often higher in urban centers than out near farms. Also, unfortunately quite a lot of farm labor is exploited and only paid per pound harvested and not even paid minimum wage. There are lots of horrifying stories about the treatment of migrant laborers, which we all should be more aware of and demand more protections for.

I totally support the vision and want to see this work, but I'm really not convinced it makes economic sense (I'd be happy to be proven wrong though).