Eating what food you buy right away precludes storing food at home.

"right away" doesn't mean the instant you get home. It's more like the next two to three days.

Yes, in an urban environment you generally have less stored food. But usually not zero stored food. You also have less space to store it in, which makes shopping every other day more convenient. Trading off time for space and whatever conveniences urban living might provide you.

Eat some food. Not all of it.

I honestly don't see how you think this is a reasonable straw man you've constructed.

Because, in my lived experience, having to carry all my groceries around did in fact mean that I was chronically short on food at home. This is a description of a real problem involved in not having a car. Calling it a strawman won't make it less of a problem.