> poor people can't afford to stock up

Sure, that's a problem. But that's not the problem I was talking about.

> have access to car shares and delivery services. Yes there is a cost, but it's usually quite cheap.

It is most definitely not cheap! You can't buy much because you don't have room, and the cost savings of what you can buy are destroyed by this added expense, making it pointless.

> most storage spaces can be optimized quite a bit

Sure - up to a point. I mean you can also just fill your bedroom with stuff, and have a narrow corridor to walk in. But realistically, people in dense cities just don't have much space for bulk purchases.

I think "1 kilo of food per person per day" is a reasonable approximation (e.g. 1kg of dried beans is 3300 calories, 1kg of canned tuna is 1300 calories). 400 kilos of food should be enough to last a family of 4 for 3 months. Efficiently packed, you can fit 400kg of food in a 0.5m x 1m x 1m space (1 large kitchen cabinet).

It's a fair bit of space, but it's not a "fill your bedroom with stuff" amount of space.

The problem with efficiently packing that is you won't have access to it easily, in order to rotate stock.

If you are not careful you'll end up with spoiled food when you need it.

Plus there's a lot more to stock than just food - It's not just about disaster preparation, we're also trying to save money and packaging and resources.

I know this subthread is talking about saving money, but imo that shouldn't be the first priority. The first priority is avoiding disaster. Insurance costs money up front. The "cost" you are insuring against is being without food after a hurricane/blizzard/etc. If you can ALSO save money up front, that's great.