with standardized marking and driver´s licence displayed
That's pretty much all taxis now. The city has cracked down (they're not even allowed to ride around at night without turning the interior light on, which I really dislike), and you'd be hard pressed to find an unmarked, pirate taxi to just jump into. All taxis should have the driver's license displayed and except for a few red-gold holdovers, which should be gone by this year, almost all are of the standard pink/white variety. There's never any 100% guarantee of taxi safety in any city in the world... even if you ask the hotel to call a taxi every time you need one, which would be a major pain, you never know who's going to show up or if you might get that one-in-a-million.