Never refer people

The Amazon review process is completely garbage. Instead of actually measuring your performance over the past year (or 6 months, since we're now in midyear review season), it's just a collection of whining complaints from people who didn't like something you said in one meeting during the year. It's completely out of context, but that doesn't matter. You can see how reviews are going by seeing how your colleagues look when they come of their meetings with their manager. Those who are being set up to be fired will be visibly upset at that moment, because it didn't matter how well they did they job. What matters is that the manager is creating a justification to fire them. The managers are completely in control at Amazon. I know people who have been screamed at by their managers, cursed at, and even heard blatantly racist and misogynist comments.

The PIP process is also the absolute worst process it can be. People get PIPs completely out of nowhere and this is considered normal.  While my personal experience hasn't been completely tragic, I tell everyone that it's a terrible company to company to work for and they should seek employment at any other high tech company because no place else is as bad as Amazon. Despite substantial incentives for getting someone hired, I never refer people.