Well, you need a cell phone to even get in, so that would likely have to change too. And then they'd need one of those complicated self-checkout kiosks where you tell how you're paying. Someone would have to deal with all the physical cash (and checks?). And at that point, you're just Walgreens.

I 100% get the logic, but for progress to happen we unfortunately need to break some norms. Like, Uber also requires a phone and doesn't accept cash... if they had to do both of those, they'd just be taxis.

Dealing with cash is expensive. You physically have to move it and protect it from getting stolen by thieves and even employees.