I'm on iOS and signed up for Uber long before the privacy scandals went mainstream. iOS would have required that I be prompted for access to contacts, but I don't remember what the justification was.
I do know it knows where "Home" and "Work" are without me explicitly telling it. I assumed I'd be able to type in the name of a contact and it'd resolve that to the contact's address I have listed (an actual valid use case), but I just tried that and it didn't work. So I don't know OTOH what valid justification they have for using it.
I do see if you go to invite friends (for "free rides"), it allows you to connect contacts to send codes to. I don't think that's how I got prompted, though.
I do know it knows where "Home" and "Work" are without me explicitly telling it. I assumed I'd be able to type in the name of a contact and it'd resolve that to the contact's address I have listed (an actual valid use case), but I just tried that and it didn't work. So I don't know OTOH what valid justification they have for using it.
I do see if you go to invite friends (for "free rides"), it allows you to connect contacts to send codes to. I don't think that's how I got prompted, though.