The Authors' Guild is doing something more like its job these days — instead of trying to tell Amazon how to run its business, it is publicizing the dreadful state of the modern publishing contract. The clauses they describe are indeed quite dreadful — like the option to opt not to publish a novel without surrendering the rights to it.
The essayist's point is that publishers — either by deliberate collusion or economic forces — have harmonized their standard, non-negotiable boilerplate contracts, and that this leaves authors with no choice: Sign the contract or publish it yourself. He goes so far as to call it anti-trust.
For the record, the book contracts I've signed have been, on the whole, fair. The only parts I've ever taken serious issue with that I haven't been able to negotiate are the occassional nondisclosure clauses. When you're writing a book where you're a domain expert, it's hard to determine what information you learned in confidence versus information you came by over your transom. The other thing I've objected to is the "reasonable" withholding against returns, which is a pretty ugly practice, since it never specifies the definition of "reasonable."
OTOH, I did turn down a nonfic contract recently, after my agent looked it over and pronounced it completely unworkable. He sent the publisher a letter asking for a real contract and the publisher never wrote back. Que sera, sera.
(Thanks, Pat!)