I am pretty fit, like I deadlift 280lbs :) and still walking with this stupid bag ruined the whole walk back. And it wasn't even much - if I replaced beer with food it would be like, 2-3 days worth.
I would have rather just finished the walk, then drove 3mins to the same store. In the most perfect conditions imaginable, with minimal amount of groceries. And what if it was 100F, or 32F, or raining, or I didn't want to go for a walk, or I needed to get some large items like sugar or rice or a gallon of milk or a lot of beer for a party?
Walking to a store is simply not an advantage at all. And if you go to even a poor country you can see most people agree - as soon as they can they start driving to big box stores, and small local stores die.
And regardless, even if (which I wouldn't grant) the majority would prefer to walk rather than drive, it's still SUBJECTIVE, not OBJECTIVE. A ton of people prefer to drive.