That's why you aren't seeing the better solution. You're only seeing what you know, which is the (tired old) signal you know how to detect. But you already detected it, and monetised it.
A better recommendation signal would be the one that you don't know how to detect. It's the signal people get unexpectedly from other people, when they chat about the thing they just bought. Call it the n+1 recommendation signal.
> The fact that you bought a ladder, puts you in the cohort of people that buys ladders, which means you are more likely to buy another one than someone who isn't on the record buying a ladder.
OK, but that's still the n recommendation signal, which has already been monetised, and won't be refreshed for quite some time, in the same way a Venus fly trap takes time before it will open and trigger again.
What can a person do with a ladder that she couldn't do before?
That question is what begets the n+1 recommendation signal. It isn't a question that even gets asked explicitly. It happens through association.
She says "I got a new ladder, and a paintbrush and some paint." and her friend says, "Oh great, I just used my ladder to hang a bird feeder from the sycamore tree!" and then she says "Oh! I've got a sycamore tree too! Where'd you get your bird feeder?"
Be that as it may it’s still ridiculous. There are very many other things I am going to buy before I buy another ladder. And Amazon should be able to know that because of having seen me search for very many other things in the past that I have not yet bought.
And if nothing else, couldn’t they let me at least click a little button next to any suggestions to tell their algorithm that no I am not interested in this recommendation?
I commented a while back on someone asking "Why recommend me a ladder if I just bought a ladder, couldn't the system understand that people usually only buy one ladder?" But the fact is, the commenter was wrong about his priors. Actually someone who buys a ladder is indeed more likely to buy another one ... even if most people that buy ladders only buy a single ladder. The fact that you bought a ladder, puts you in the cohort of people that buys ladders, which means you are more likely to buy another one than someone who isn't on the record buying a ladder.