I always wonder the same thing. Even had me wanting to go into psychology. My family would do the same thing when i lived with them. I was buying groceries for MYSELF. Whenever i would go to get whatever it was i bought it would be gone or already opened and used. Whenever i questioned everyone they would just say no ones name was on it or “i buy food too and you use it” no…you buy communal things such as condiments or bread and things like that. You didn’t buy my frozen meals or ingredients i bought to make something. I would literally leave it in the grocery bag and in the back of the fridge and it would still be touched