If there are differences it'd be (partly) b/c of regulation which the topic is all about. By all means if Uber feel like using licensed drivers, cars etc. as they apply to a specific country, they can keep their ubiquitous app.

For instance: enough cities may not have preferred/dedicated public transport lane which makes significant costs based on waiting times, rather than distance: hence pre-agreed price is an estimate at best.

To me: Uber is a taxi company through and through and if there are local regulation Uber should not be able to circumvent them.