I am not sure if I agree with you on wage distributions.
Sure, Google and FB pay more and so do top investment banks / hedge funds in math/stat/algo positions . However, those simply are not the bulk of fintech employees.
The majority of fintech SDEs at GS,Morgan,etc. are working on software engineering and maintenance work. These roles pay closer to the $100k number than Amazon's quoted $150k. At least for new hires.