In short: "Extreme programming fails because it requires trust."
Disagree!
Boiling it down to one word doesn't do the problem justice. Do you trust your developers with your code? Do you trust them follow code standards? Do you trust them with business secrets? Do you trust them with your house keys? Those are all different levels of trust. How do you implement a process with people who don't trust you or otherwise undermine attempts at change? Knowing what you're up against is more than half the battle.
How do you develop with developers you don't trust? I think that's the wrong question.