What you're missing is that people are intentionally hired and set up for failure from the start. This seems to be standard practice at Amazon. You can't just fire people randomly, there is a whole process including documenting how the employee is falling behind and giving the employee a warning and a chance to dispute, etc. Setting up a new employee for failure by abusing the internal processes, setting up roadblocks and giving them unreasonable tasks or incorrect requirements is pretty common from what I've seen.