Re: So Amazon paid $5Bn in various taxes
Yes, this is very significant. All those RSUs vest and they are typically* taxed as ordinary income at an individual's marginal tax rate at the time they vest. So you pay federal, state, local, and FICA taxes.
* unless you opt for Section 83(b) Election (which most people don't) in which case you had better stay at the company long enough for the stock to vest or you have paid a lot of tax upfront (on the day of the grant) and the shares never vest.