In the beginning when Uber moves into a new region, they pay drivers well to get drivers onboard, and charge riders little to get riders onboard. This also makes competitors like taxis less attractive and makes Uber really popular, making it hard for the city to push back.

So drivers might be getting more than riders are paying, with Uber subsidizing the entire thing! If your city is in this phase, it's great for riders and drivers.

Once they're established though, and the competitors have been pushed out, and people learned that Uber is awesome and cheap compared to taxis, they start raising prices and reducing driver pay. To keep enough availability they need to hire new drivers, which means their quality standards drop, and they use increasingly creative strategies down to debt slavery (desperate drivers lease/rent their car - which can be their only vehicle and which they may need to get to work or exist in general in a car centric area - from Uber, at "very favorable" rates. But then they have to keep driving for Uber or lose the car.)

https://www.theguardian.com/commentisfree/2019/dec/05/uber-loan-program-debt

They also exploit that most people don't realize the true cost of a car. They only look at gas, not the wear and maintenance of the car. And if you look at what Uber pays, deduct only gas, and consider the rest income, it looks like a good deal, while in reality they might be selling their car to Uber one kilometer at a time and working effectively for free.

As I understand it there isn't a direct share of the ride price or anything like that. The amounts Uber pays to drivers and charges from riders are decoupled to the point where even way it's calculated (e.g. actual distance vs. scheduled distance) could differ between driver and rider. The driver side fare system is different per city/region.