Between 2014 and 2015, Uber secretly tagged iPhones even after users uninstalled its app as a fraud detection tactic and hid this from Apple engineers, according to a report by the New York Times. The practice, known as "fingerprinting," is not allowed in that form under Apple's rules and earned CEO Travis Kalanick a meeting with Apple's CEO, who was understandably not happy and threatened to kick the ride-hailing company out of the App Store.

Uber trend: Allegations of breaking, ignoring, or bending rules are nothing new for Uber, which has used aggressive tactics to fight off regulations and competitors alike. Until recently, for example, Uber used secret software to evade local law enforcement, and built a way to track drivers who work for its main U.S. competitor, Lyft, to target them with incentives to remain loyal.

"Devices fingerprints are a common technique used across the industry for a variety of security purposes, including fraud detection," an Uber spokesperson told Axios. "It's also the method through which service providers can authenticate a 'trusted device' on your account."

Uber still uses fingerprinting but has modified it to comply with Apple's rules, according to the spokesperson.