SEATTLE — When Kristi Coulter sat down to write a book about working at Amazon, she kept hearing a voice in her head. "You were terrible at your job, and you're not good at this," the voice said, which also told her that her memoir, published last month under the title "Exit Interview: The Life and Death of My Ambitious Career," would be a failure. This was the Voice of Amazon, Coulter said. "Amazon is not a place where you really get told you're doing a good job." It's a place, as she describes it, where no feedback is good feedback, "where you never feel like you're really nailing it," and w...