I find it odd that Uber is constantly fighting various countries' laws to be considered "a taxi service, but not a taxi service", when they could just change their business model a tiny bit and fall straight into the middle of the "limousine service" classification. Why not charge just-time instead of time+distance? Would it screw over the drivers?
Distance + time is the most fair solution, as if there's no traffic and you get there super fast the driver still gets a fair fee (unlike if it was time only), if there's lots of traffic and it takes ages to get there then the customer doesn't have to pay a huge fee (like if it was time only).
Personally I'd never use a taxi service that charged only by time. I'm OK with time+distance, or with distance only (which is also used in some places).