Or when you just landed on the other side of the planet and don't have a good internet access (or it costs $$/Mb): the app is still expected to work, because you need your ride right now
Uber doesn't work without decent internet access though. Maybe you can make he argument for $$/Mb, but there's no point in uber creating the app so that you can get to the pay screen without internet when you need the internet to use uber.
Decent can still be pretty bad and still work. And of course it's worth it because a phone can find/lose it's connection all the time for a bunch of reasons even if the network is high quality and high bandwidth.
The whole point is the seamless transition. Would you want to sit there twiddling your thumbs in a potentially unfamiliar area, while the region's version of the app loads? Or would you rather just have it work?