I understand your point and quite frankly, you are right about the supplies getting low, without them noticing the obvious...more needs to be bought sooner than later.
Because I did all of the family cooking and shopping, I would look in the fridge, pantry and storage areas before going shopping so I could add things to the list. Like you mentioned, I noticed when supplies got low before running out. Sometimes my kids would say they were out of their shampoo or the ketchup is low, but I would typically be in charge of the grocery shopping, so I made it my job to be aware of what we needed in the household.
Fast forward twenty years...kids grown, moved out on their own. Divorced by now and living alone, growing accustom to this new great lifestyle. Yay!!
Until..........My sister came to live with me for two years. She, like me, cooks and of course uses the household products and we often shopped independently. Well, she would use the last of something and not tell me. Or, we both realized something had to be restocked and we both bought it, creating doubles. We devised a simple solution. We kept a running list on the fridge for things that ran out or that we needed. Never again did we ever look for something to find we had none left. So, my suggestion is to create a list that everyone uses when something is about to run out.