Flagfall, or flag fall, is a common Australian expression for a fixed start fee, especially in the taxi, haulage, railway, and toll road industries.
The logic behind it is believed to be a method used by Australian mobile phone companies to recover a component of the carriage charges that they incur in completing a call to a subscriber.
The taxi expression is also being used in Hong Kong, New Zealand, and some other countries, but it has not been used there as a general synonym for a start fee.
The term "flagfall" dates back to the old mechanical taximeters, which were equipped with a flag-like lever that could be seen from outside the cab.
When a passenger stepped in, the driver turned the lever down, the "flag fall", and the taximeter started counting.