The point I am trying to make is that there is a point where it isn't a question of merely being inconvenient, but practically impossible.
Working 40-80 hours a week, with no paid time off, and caring for kids, does not allow for a lot of time to spend on buses to shop for food several times a week.
If you go by bus, you are limited to what you can physically carry. That means you can't do all your monthly shopping in one go. No car trunk to carry things in.
If you have two or three other human beings to shop for, that means constant trips to the store, even if the store is close by.
The only way this is sustainable, is if you give up exchanging work hours for food shopping hours, adding to your costs.
time = money at some level
That is the point.