The hangup calls were the side-effect of their extremely aggressive recruitment efforts for Lyft drivers - where it seems they'd hang up and call back later to try and get a different driver that they hadn't already pitched.
While not great, it also doesn't strike me as particularly underhanded or evil (this is a scenario where the "best" outcome for Uber is paying Lyft for a ride where they try and give the Lyft driver a phone and presumably a better paying job).