Mostly because markets deliver a less consistent experience (delays, cancellations due to vacations), and you face situations where your employees and customers

Mostly because markets deliver a less consistent experience (delays, cancellations due to vacations), and you face situations where your employees and customers are fighting over the last bag of chips. It also becomes harder to plan logistics because most stores (at least where I live) have limited real estate. The semi-automated ones have different issues. Only Amazon really has the tech fully figured out to a degree where issues are resolved almost instantly. Amazon can also use less but larger scale fulfillment centers because they deliver mostly small objects at an arbitrary time, whereas you can't leave 6 bags of groceries at a front door.