Thank you for the responses everyone :-)

That makes sense, but I was curious as to how Amazon can tell the difference between a deliberately lowered price and a third-party's internal decision to discount books.

For example, some sellers might display: "99c discounted to 80c"

Whereas other sights simply show the lowered price, giving Amazon now way to tell if this price was set by the author or set as a result of a rival store's discount decisions. For example, Kobo does not mention its discount percent, whereas Amazon always shows how much its discounting if there is one.

In the latter case, an author would not be at fault.