Thanks for your answer. I really didn't know. I've only taken a cab a few times in my life, and those were all for business trips almost 20 years ago where it made more sense than renting a car due to short distance or due to being in NYC....You can not reject someone who hails you or approaches you on a street or taxi stand. You can reject trips that pop onto your screen. That is the substitute for your Right To Remain Silent that obtained in the days of voice dispatch (READ: REAL dispatch).