Walking to a store everyday to buy only their daily necessities would end up costing them a lot more than if they were buying a bunch of what they need in bulk, and nobody ( especially an elderly person) is going to walk home carrying around their items in bulk sizes.

Even for people lucky enough to live in those rare areas where you can walk to a grocery store, it's extremely useful to have access to a car you can fill up with large items.

Daily necessities and daily excercise. For some of these people it's the part of the day they look most forward to.