That's one of the reason people hate taxis, and why people jumped to Uber instead. Who's to stop the driver from taking the long route, and how am I supposed to compare options if I don't know how much it will cost? Pull out a pocket calculator and a map?
Many cities have a set rate for airport-to-downtown trips, and you may be able to negotiate one directly with the taxi driver for long or unusual trips.
> Taxis at JFK Airport charge a flat fare of $52 for trips between the airport and Manhattan. Taxis impose a $4.50 surcharge during peak hours (4-8 p.m. weekdays, excluding holidays), for a fare of $56.50.