Which raises an obvious asymmetry: Amazon makes no guarantee that it is not offering more favourable terms for bigger suppliers – and although mere speculation, I would be surprised if that didn’t go on, because I seem to remember traditional retailers doing similar things.
I’m not saying this is good or bad, just pointing out that with all retail there has been almost a phase transition once the supplier is a household name, and the dynamics change almost to the point where retailers would offer their products at cost price or even a loss just to make sure that their customers could buy the household name through them.