I have taken hundreds of taxis in China, black cars, metered taxis, touts from the airport... just about everything except a rickshaw. Some drivers do legitimately get lost as the streets are not always marked the best and there is so much new construction that things change on a daily basis.

The cost for the taxis is so cheap compared to the US even if they do jack you a bit on the price its not a big deal. I don't believe they try to gouge foreigners in particular as I have often asked the locals what they paid and its usually about the same.