It can be tricky and getting murkier quick: what if Google comes back with an argument that that data scientist would not have been able to produce those $2-3 m

It can be tricky and getting murkier quick: what if Google comes back with an argument that that data scientist would not have been able to produce those $2-3 mil without the resources and the infrastructure made available by Google? Would that employee be as productive anywhere else? If the answer is yes, then that employee deserves a larger share of the pie. If the answer is unclear or no, then the employee will receive whatever the market will bear. This is why traders and IT devs on Wall Street get better compensated: it is way easier to see the exact impact and it is very likely that those guys would be able to easily replicate it in any other firm.