I have to assume that those who have a total free for all system, no one asks anyone, everyone helps themselves to whatever is there... has endless cash and time to replace things.
It is easy here as theres two of us and only one of us can cook or get in the freezer, fridge or half the cupboards.
But previously, in houses shared with more than one person, it was pretty simple and common sense to work through:
Did I buy this for me?
Did someone else buy this and are they they one cooking over the next few days?
Is this the last of something or is there plenty?
Might this be a vital ingredient to something someone else is making?
Did I make this?
Is there anyone around to check?
Could I have something else if I am not sure?
So if I went in the fridge and theres a bunch of expensive ingredients I did not buy, its not me cooking for the next few days and I could have a toasted sandwich or bowl of soup etc instead, and there is currently no one at home to ask - I'd have the sandwich/soup - not scoff half the ingredients for something someone else was planning on making.
If someone else has baked a tray of cookies, I might ask if I can have one if theres someone to ask. If there is no one to ask I'll leave them alone, I didn't make them and I don't know what purpose they're for.
But if theres a full loaf of bread, a full tub of lurpak and a jar of marmite, no I wouldn't be texting and hunting down every resident to ask permission to eat a couple of slices.
I think this is called being considerate and thoughtful towards those you share a home with. Clearly some Mumsnetters don't think thats necessary.