Levandowski can't be all that smart if he thought he could download 14,000 documents onto his work laptop, without Google noticing. I mean, hello? Any sane I/T security protection architecture would assume that despite the best security you can put on employee's laptops and mobile devices, a sufficiently determined criminal or state actor is going to be able to get onto the laptop.
So having extensive monitoring on work machines is not because you don't trust your employees --- but because you don't trust that the employee's laptop / mobile device is always going to be under the control of the employee. And if it does get compromised, you want to be able to state with confidence how much data might have gotten compromised, or how much access the criminal or state sponsored attacker might have been able to gain access to.
The fact that it can also be used to find incriminating evidence for back-stabbing employees who are intent on screwing over their employer is just a bonus.
And if he wasn't smart enouh to realize this, I wonder how much Waymo lost and how much Uber gained when they lured him away from Waymo. :-)
The next Levandowski will think twice before following in this one's footsteps - even if their actions would be 100% legal. The next Kalanick will think twice before hiring him.