I also don't fully understand the attention given to home consumables in these kinds of IoT applications- for me devices like Amazon's one press ordering button thing are better for this type of problem as it keeps you in the loop while still saving you the time. It's actually the automated purchasing that saves me time - not the automated sensing that something is running out. I already see that incidentally (often as part of my day) and in a second.
Edit: the physical re-ordering button I referenced is called the Amazon Dash; it's not exactly what I thought it was but it's pretty close.
