Great point on the driver calling being an issue for non-Mandarin speakers. I also experienced this. I actually asked drivers why they do this and apparently riders seem to put incorrect location information in -- this in itself indicates there is some problem.
Regardless, I don't begrudge Uber much here; the driver call culture is hard to fix (even in America, I'm called sometimes) and it's not unreasonable to require your customer base speak the local language. (It is unreasonable though for the phone app to assume your locale matches the local language [help screen problem] or to assume that you've downloaded the app from a completely local source [Google maps source issue])
