In a German city, taxi fares are set by ordinance. The Passenger Transport Act lets the state government fix them, and it may pass this power on by ordinance. The fixed fares dürfen nicht über- oder unterschritten werden. They may be neither exceeded nor undercut, and they must be applied equally to every passenger. The driver cannot give a discount, and the passenger cannot offer less.
The law now has one opening. For trips booked in advance, the ordinance may set fixed prices, or a minimum and a maximum within which the fare is agreed before the trip.