This isn't the right place for discussion about the battery API
- there are certainly valid reasons why a web app may wish to know the battery status, and those should be brought up with the Device & Sensors working group in the W3C. Their mailing list is here - http://lists.w3.org/Archives/
Also, Uber is not and has not to anyone's knowledge done anything with battery level. The original mention of them seems to have been due to a misreading of a comment about how people with low batteries are more likely to accept surge pricing. Uber also does not have a web app, only a native app, where battery info is generally available.