The paperwork gives as an example a $55 toy that is sold by an FBA member that is featured in the Buy Box while a non-FBA vendor that offers the same item for $51 is placed in an alternative sellers box lower down.
Not mentioned: the FBA product almost always qualifies for free shipping in orders over $35, or free Prime shipping, while the non-FBA product almost always has an additional shipping cost. This means that the one in the buy box is usually the cheapest when you account for shipping (and also means shipping is faster, and combined into one box where possible).
If that’s the logic they use (and from an end-user perspective, it appears to be) then I’m totally fine with it.
Not mentioned: the FBA product almost always qualifies for free shipping in orders over $35, or free Prime shipping, while the non-FBA product almost always has an additional shipping cost. This means that the one in the buy box is usually the cheapest when you account for shipping (and also means shipping is faster, and combined into one box where possible).
If that’s the logic they use (and from an end-user perspective, it appears to be) then I’m totally fine with it.