It's not just battery level; it's where you want to go (shoot'em up neighborhood), time of day, number of drivers in the area, credit score, ect.. Welcome AI; It's a supply vs demand automatically adjusted pricing model. More available drivers, lower cost rides - less drivers, higher cost rides. This is what really happens when you click OK to their terms of service agreement........
A supply vs demand pricing model is at least something familiar: when there are lots of people wanting rides compared to available drivers, price goes up, and so on. Aggregate numbers. We learned that version of supply vs demand in school. The brave-new-world part is mining your phone to compare your personal 'demand' to the available drivers and set your personal price. Your demand is high right now because it's dark and you're miles from your home and your phone battery is about dead and your playlist suggests you'd not be comfortable in the neighborhood you're in. Here's your price.
Praise or curse AI for optimizing the pricing of your ride......... If you've ever search the price of airline tickets, then cycle back to the lowest cost carrier - you'll likely find the prices has increased. Clear your search history and cookies, you'll likely see that low price again. Skynet is a hoax......... Don't worry, your private information is still intact, unless the company gets hacked or sells your information (ie. pending sale of 23andme).