When you arrive at an airport, there is usually an organised taxi counter where you can wait in line to take a taxi to your final destination.  There are two issues with these.

1) There is often a long line – The last thing you want to do after a long flight is to be waiting in line after a long haul flight.

2) There is usually an additional airport charge which gets added to the Taxi meter – Sometimes it is a flat fare which works out a lot more expensive then the meter fare.

A great trick is to make your way to the departures drop-off point and get into a taxi that is just dropping off a passenger.  While some airports frown on this, it is impossible for them to monitor and control.  It means you don’t have to wait for a taxi and you avoid paying extra airport charges.

Airports are usually a considerable distance outside of town.  When a taxi driver takes a passenger to the airport, it does not make sense to drive all the way back without picking up a new passenger.  However, due to the high number of passengers wanting a taxi at airports, there are usually a lot of taxis waiting for arriving passengers.

A taxi driver will therefore have to wait some time before getting to the front of the line to pick up passengers.  By picking up a passenger at the departures hall, they can save themselves a considerable amount of time.

The end result is a cheaper fare for you, very little queuing and no waiting for the taxi driver.  This lets you get to your destination faster and at less cost.