There's a difference: Amazon
can pay more. As you said, the millennials
can't. If there's a millennial out there flush with cash but didn't get the house they wanted despite having $$$ more than needed, then yes-- that would be their own choice. Just like it's Amazon's choice to live with a driver shortage if they
can pay more but
won't.
Based on their 2020 profits, they can pay more. $20B in profits, 170,000 deliverers worldwide. They could take 10% of that and pay those folks an average of about $10,000 more/year.
They have the money, so if their business suffers at all as a result of too few drivers, then it's absolutely self-inflicted.