I think it really depends on your situation. Some people, especially in North America, live so far from the next supermarket that going there every couple of days just isn't realistic. Plus remember, we still live in a pandemic when people might want to limit their time in public closed rooms like supermarkets and try not to go shopping too often.

I live in a big European city and have multiple supermarkets in walking distance. So before the pandemic I would rarely go out specifically to buy groceries, but I would just casually pick up a few things on my way home every couple of days.

But these days I'm also carrying home heavy bags of shopping once a week. And I'm only shopping for myself, I guess for a family 70 pounds isn't actually that much. Plus I drink tap water, but some people may even need to buy water, which is obviously heavy...