I think with FAANG it’s mostly just down to them having insane valuation and being able to give out those stock options. The base salaries don’t seem particularly high, until maybe the highest levels.
It's not just insane valuation. If the employees are bringing in $1M per head, you can afford to spend more on those who are making stuff.
The cash and other benefits are still ludicrous by any normal assessment but stock makes it unreal.