Amazon recently sent out an email informing drivers that the terms of service has been updated. I’m no lawyer so I choose not to speculate on it. If you’re looking for a searchable version, here it is, copy and pasted directly from the Flex app on 10/8/19:
Old TOS:
The old TOS from 2018 can be found here: https://web.archive.org/web/20180516093840/https://textuploader.com/df6iz
Differences:
Diffchecker is a handy tool for comparing text documents. In this link the old TOS is on the left and the new one is on the right, differences between the two will be highlighted.