I presume he orders online. I'm not sure what it's like where you are but here I order online from the largest supermarkets (Tesco, Asda etc.) and have it delivered to my door the next day for a £3-5 delivery charge. It's pretty commonplace.
That isn't commonplace in the US which I assume that is where he is from considering the whois info.
In fact it would probably be much more expensive here.
The main choices probably are a family member picking up groceries for you, or a small market which still can deliver groceries, I know mine stopped offering delivery around 5 years ago because the community size grew so much.
Though I'm UK-based, not US, I'm a housebound agoraphobic (I don't leave at all, ever) - you'd be surprised how easy it is logistically in this day and age, actually. I have family members pick things up that are time critical (ie. my dumb ass forgot something I'd need) but other than that everything is deliverable from somewhere.
Though I don't have any metrics on how "commonplace" it is, it is pretty accessible in several urban areas (Portland and other Oregonian urban areas, Seattle, LA and other SoCal urban areas, San Francisco, and New York off the top of my head) and the price is only slightly higher than what k-mcgrady quoted. In Portland, if you're okay with a four-hour window, Safeway charges ~$7 USD. A one-hour window is ~$13.