Contracts are already interpreted against the drafter(s), because they are in the best position to have written their intentions. Businesses are also held to the express language of a contract because they are regarded as having the resources to hire legal advice. However, individuals are not held to the same standards, because they usually lack the knowledge, experience, and resources to understand the import of the language in most contracts, expecially those drafted by lawyers for large businesses. In such case, they will simply be required to show that their interpretation of the contract was reasonable.

The authors did not write the Amazon publishing contracts. Most of them aren't lawyers, and a lot of them may not even be college graduates. They cannot, and legally will not be held to a strict reading of the contract if they can prove that they reasonably believed that the Lendle program was limited (or marketed as limited) to friends and family of the ebook purchaser.

BTW, that's not the most expensive comma. Check out the comma in the Cleveland Browns contract that cost Cleveland a Superbowl-winning franchise. (The current Browns are an expansion team.)