Most people don’t have the space or the cash to buy a few extra every month,and even packaged foods go out of date as does paracetamol/calpol
I don't think that's true at all. Obviously there are people who have no spare money and/or live in very small properties, but it's far from 'most people'.
I'm not talking about having months worth of supplies, merely not leaving until you actually need something to buy it. Operating on a 'just in time' basis and buying week to week, leaves you very vulnerable if there are any supply issues or reasons why you can't get out, as people have discovered.
We've always shopped for a store cupboard not what we expect to use week to week. So will buy a 4 pack of beans for example and then get another one when we're down to the last two, that sort of thing. Buy another shampoo when the last one in the cupboard is opened, not when it is nearly running out.
It is also far cheaper to shop this way, because you just buy things when you see them on offer, you are never forced to buy a high price item now because you need it now.
Excluding the people who have no money obviously, it can't really be said that 'most people' can't afford to do this. Our stocks are worth maybe £100-200 at most. You can't really say that 'most people' don't have a spare £200 when they often spend hundreds of pounds a month on entirely discretionary items. Plus as I said it actually works out cheaper to keep a store cupboard so easy to do once you get into the swing of it.
It doesn't take much space up either. We live in a small 2 bed house with a very small bathroom, and the shampoos, toilet rolls etc are in a tall cupboard (cheap from ikea, so that's not expensive either) and the rest of the Costco toilet roll is under the bed.
The spare beans are just in the one tall kitchen cupboard with the normal beans.