Lyft already has the full implementation in their app. Uber has a beta sign up list and a blog post. Occam's razor says that Uber got wind of this launch and quickly wrote up a blog post announcing the same thing in order to spear it.
To be fair, SideCar launched this feature a good deal before either of them.
I'm sure both Uber and Lyft were aware of this feature being designed by their each and are trying to get their respective features out the door.
Ever notice how AWS and Google release price decreases within the same days? Same thing. They have been told it is upcoming and are doing the same thing. I've seen it personally.