This article seems credible: https://pando.com/2015/01/09/the-hidden-cost-of-being-an-ube...
But, what it shows as the "income after op cost" isn't the real truth. That figure ($12.62/hr in Chicago, $34.04/hr in NYC) would be basically 1099 income. You would have to pay self employment tax (not trivial), and forgo whatever benefits a cab company might provide their employees.
If you look for average salary for cab drivers, and compare to the above, you would gather that cab drivers do better than Uber drivers in Chicago, but worse in NYC.
I can't find any credible sources where it seems 100% clear that the comparison is thorough, and apples to apples.