Uber actually has a not-so-well-known product for this very problem: the mobile web version (m.uber.com)
It doesn't have nearly as much functionality as gregdoesit mentioned, but it's enough to service the use case of getting you from point A to point B when you're stuck w/ crappy connectivity.
The other not-so-well-known product is the Uber Lite app (iOS and Android) which was specifically made by Uber for this problem, particularly in the developing world.
Why display a link? Hybrid web/native apps are a tried-and-true strategy when you have massive complexity or dynamic content that you don't want to ship with your app. If you use it judiciously and tastefully the "native UI everything" people don't notice and come after you, either.
I actually built this product out (for both Uber and Lyft) - SMS/MMS-based ride requests (MMS only for sending google maps PNGs to confirm pickup location). I was about to convert it from a personal project (I used it to get rides on both services for a few years) to a "real" one open to customers, etc and then ran into snags with both APIs at around the same time. Uber's API changed to potentially require a web flow to confirm surge pricing (IIRC - now it's scheduled to be disabled entirely very soon) and Lyft's API was basically shut off entirely (there's a way to apply but I was unable to make any progress even through internal contacts at Lyft). I'll try and keep an eye out for any changes...
It doesn't have nearly as much functionality as gregdoesit mentioned, but it's enough to service the use case of getting you from point A to point B when you're stuck w/ crappy connectivity.