"Subscribe and save" is a scam.
They advertise that you will save 5% by using subscribe and save, but then the price of the item you are buying just happens to go up by 30% on the day they decide to use as the basis for your order, which is not the day you ordered it or the day they pulled it off the shelf. It will occasionally go back down to a normal-ish price, but there will also be random months where it goes up 50% or 100%. I've seen $15 case of paper towels go up to $45 some months.
Then they keep prodding you to add more items to get 10% off your entire subscribe and save. I added some items a few weeks ago, got the extra discount percentage, but when they priced my order a few weeks later, the cat food I've been getting from them at a pretty stable price suddenly went up in price by the exact amount the extra discount was saving me.
Amazon essentially took the "four square" concept that car dealers use to shift higher costs to an area of the transaction where you are less likely to notice it.
You're looking at it backwards. Look at it the ultra-wealthy way: you are the dependent your dog claims on his taxes, but you do all the work and pay the bills. The money just passes through you to accomplish these things, but it's not your fault your dog can't read the tax code.