Here in SP people use it only because of the price (about 30% cheaper than taxi). Uber Black was here for some time and no one never noticed. Only when they came with cheap UberX that people started using.
But taxi lobby fought back hard and Uber is oficially forbidden here until further regulation (unoficially still running though).
Anyway, just to share that here in SP is mostly a price competition. Not much else.
EDIT: Just for curiosity, the two bigger taxi apps in SP 99Taxis: https://play.google.com/store/apps/details?id=com.taxis99&hl... Easy Taxi: https://play.google.com/store/apps/details?id=br.com.easytax...