Great explanation of Uber's smoking policy (or lack of):

http://ubercustomersupport.com/uber-smoking-policy/

Uber calls themselves a tech company, and the driver are merely users of their app / independent from Uber. I'm not sure why people are expecting Uber to do any type of enforcement. It's not a taxi company and the drivers are not licensed drivers. The most Uber will do is kick the driver off the platform if there are a high number of complains. So you as the rider have the option to leave a 1* rating, or cancel the ride if you don't like the situation (I hate the smell of smoke so I would have just cancelled the ride).