They don't. Kinda. They pay for the service but BTS argues that they are not paid enough to be able to provide higher wages.

It's like the FedEx Ground model. Amazon is paying the contracted service provider (BTS) X amount for the route + Y amount for every stop and package, and fines them for various service failures and issues.

It's on the service provider to then use that income to pay their drivers appropriately themselves.

BTS rolled over because they literally can't do anything from a management perspective regardless if Amazon won't give them any more money to do their job and pay downwards to its employees. Amazon will just simply choose to stop doing business with BTS as a whole and move on from this and screw them all over.