Desk research against primary sources. Figures are traced to the issuing UAE authority and linked on the page.
The flag fall itself already tells you something about the trip’s likely cost profile — AED 5 from a standard pickup versus AED 12 starting from DXB reflects the airport surcharge built into the fare from the moment the meter starts, not a different per-kilometre rate once you are moving. Both figures assume the meter is actually running, which is the entire point of an RTA-licensed taxi over any alternative.
An unmarked car offering a ride outside the app or meter system is not a cheaper version of a taxi, it is an unlicensed one, which means there is no fare regulation, no meter reading of roughly AED 1.96/km to fall back on, and no operator to complain to if something goes wrong. Sticking to a metered RTA taxi or an app with upfront pricing removes that risk entirely rather than just making it statistically less likely.