Taxi and car-sharing apps which quote for journeys based on GPS data could find themselves outlawed by regulators. Transport authorities across fifteen US and Canadian cities are looking at a set of rules that would prohibit anything except physical metering to calculate the cost of a trip. The proposals would also put the kibosh on demand pricing, whereby quotes automatically rise when more people are making bookings, and also on the use of drivers who don't have proper taxi licenses. Some of these practices are already banned in a number of states, and in fact three online transport services -- Zimride, SideCar and our old friend Uber -- were fined in California this week precisely for allowing unqualified hands to take the wheel. If the current proposals are adopted, the role of smartphones would likely be restricted to hailing regular taxis or putting electric money into traditional cabbies' pockets.