You don't understand Amazon's pay model completely. They have a backloaded vesting structure of RSUs, sure, but Amazon also provides a cash 'signing bonus' that vests monthly over years 1 and 2 in an amount that gives approximately the same total expected yearly comp for the first 4 years (same as calculated at time of grant; subject to change with stock movement).

My Amazon comp has been more than competitive with FB, Uber, Google.

[Disclaimer/Source: work at Amazon]