#1 - was this because you were still using the US store downloaded app? I highly doubt they would release Uber to Chinese people with a non-working maps.
When I was in China early this year, they use baidu map on my iphone version. It looks like there was a partnership between baidu and uber back then. There's even a "get Uber" feature build inside Baidu Map app back then.
But this is what I mean as an example of an easily fixable problem. If user is using the Play Store app, show a dialog or otherwise redirect them to another source. Even a simple help menu telling you about the problem and how to fix it is low-cost.