Here is a recent example: Lawsuit accuses Nvidia of stealing trade secrets — perpetrator busted with a screenshot of stolen code | Tom's Hardware. While we don't know for sure if Nvidia was involved in the theft, here is what my insider view brings to the picture (and here, you can trust me or not):

1. While working for Valeo, it's impossible to not know the consequences for stealing source-code and other secrets. Like most companies of this size, you need to go through this wonderful "anti-trust, bribery and compliance" training every year, with a test and signature at the end. This guy knew what risk he was taking by stealing source-code. Personally, I wouldn't take this risk unless I am offered with a life-changing amount of money.
2. I know from former coworkers with similar profiles than mine, that while they were paid ~85k€ at Valeo, Bosch will get you ~75k€ and Nvidia will take you for ~115k€. They definitely have a good budget to get engineers out of the competitors.

P.S. I realize this is not proving anything and it sounds mostly like "trust me bro". Make of this what you want.