Because it's spoken like someone who has never dealt with human resources inside a company. The people making more money have more options - they'll just leave Amazon.
Each role has it's own supply and demand. You can arbitrarily start paying less for a role and not expect there to be a negative impact.
You (and others, evidently) don’t pick up on the tongue in cheek nature of the comment. We all know we can simply raise pay at the bottom without needing to cut (or inflate) anyone else’s pay. They are similarly absurd propositions.
Each role has it's own supply and demand. You can arbitrarily start paying less for a role and not expect there to be a negative impact.