[YoAdrian]

Why would "conventional thinking" expect them to use Androids?

These are the drivers' personal cars and the drivers' personal phones. That's like saying "conventional thinking would expect Uber would have them all drive a Prius."

[hashtag]

I don't know whether or not OP is correct in thinking that Uber drivers' use iPhones only, but I know that for the Uber rides I've been on, the drivers certainly have an extra phone that they use for Uber (I assume company issued) in addition to their personal phone.