Another "too obvious" way of walking home groceries is to use a suitcase on wheels. Or a hand-drawn cart.
Very true. There were two main reasons I found backpacking easier in my circumstances and neighborhood:
1. Icy (or absent) sidewalks, steep hills, can make it harder to push a cart.
2. It was easy to walk the groceries up to my no-elevator third-floor apartment with a backpack.
My grandmother lived alone in her house until age 93, never owned a car -- she used a bicycle with saddlebags for all her shopping, plus a walker at the end. It was quite a sight to see her hauling her groceries around, especially pushing the walker full of groceries up the steep driveway to her house.
There's some luck and genes involved in staying this healthy, though, even as much as her lifestyle contributed to her good health. Sending my dad out on excursions like this would be a recipe for a massive heart attack.