When companies pay each engineer X and earn 10 times X on each engineer, this is inevitable. Near as I can tell, this is a strategy that is helping engineers retain more of the value they are creating. If the difference was more subtle such as 2 to 3 times X, then the incentive to go through this much trouble to retain much of the value you create is much smaller.
Google was already at the center of the high-tech employee wage-fixing earlier this decade, so filing lawsuits to create deterrence wouldn't be that surprising.
https://en.wikipedia.org/wiki/High-Tech_Employee_Antitrust_L...