They're adding functionality that Apple refuses to do.
Apple refuses to do it for a valid reason, and I see Apple as the ethical winners here. If Uber is experiencing a high rate of fraud, that's a business process problem that needs to be addressed within Uber's own internal systems. Considering Uber can afford a "competitive intelligence" team that buys and crunches data about Lyft, and they can afford to develop "Greyball" deception tools to evade law enforcement, they should also be able to afford a couple of employees to build some better fraud detection into their signup process. A little less offense and a little more defense might be a rewarding strategy.
Thousands of other companies conduct business via iOS apps without resorting to breaking the rules. Uber is showing once again that they don't give a fuck about the rules, and that puts them squarely outside of the "ethical right."