Buzzfeed has a baffling article up about how Amazon and Overstock are waging a price war on physical books featuring deep discounting and huge wins for consumers. According to Andy Meeks this leaves authors "authors caught in the crossfire." Meeks doesn't do anything to explain why this is bad for authors, but he does quote one book author tweeting about the price war. Then Meeks says "what’s even worse for authors is that the battle is only in its initial stages and is likely to get more intense as it continues." But again there's no explanation of why this is bad for authors.
The answer is that it isn't bad for authors.
Authors are paid by publishers, who hand out advances and royalty checks. The royalties are based on a percentage of publishers' gross revenues so the retail price of the books sold doesn't mean authors get less money. If anything, retailer discounting is good for authors and publishers because it boosts book sales.