Just spitballing here, but if you just bought a mixer, your odds of buying another mixer is lower than that of buying a cook book or some other related stuff -- which Amazon could totally figure out mining the other stuff people bought at the same time or shortly after a mixer.
It's still not necessarily the better idea for them.
Some percentage of people who just bought a mixer will get a product they aren't satisfied with, for whatever reason. That population has a much higher change of buying another mixer than other people. And mixers are probably far more expensive products.
I have no idea if, in an absolute sense, there's more chance you'll buy a cookbook rather than another mixer, but it wouldn't surprise me either way - on the one hand, obviously most people don't need two mixers. On the other hand, plenty of people who buy a mixer will never buy a cookbook in their life, but literally 100% of people who bought a mixer have proven that they were at some recent point in the market for a mixer. I'm not sure which effect wins out here.
