Do people generally not have space to keep 7 days of groceries on hand?

I mean, I get some folks are houseless which obvs, they can't do this...

But I am hard pressed to figure how someone can't buy an extra canned good on a shopping trip? That's literally 0.79. 2l bottles of soda aren't things people.buy from time to time? Can't harvest them from recycle buns?

I think a lot of this is looking at the end result, and seeing it to be impossible, because they are trying to eat the elephant in one bit, rather than just one bite at a time...