He has no choice but to travel in taxis in which there is haraam music
Question

                What should a person do if he has no choice but to ride in a taxi and there is haraam music in it?.
Praise be to Allah.
    You have to advise those with whom you travel in taxis in 
    which there is haraam music not to tune the radio in to music stations, in 
    the hope that they will respond to your advice and refrain. If they heed 
    your advice then praise be to Allaah, otherwise then you should get out and 
    leave them to their misguided ways, so as to protect yourself from listening 
    to evil. If it is too difficult for you to get out for some reason, then 
    there is no sin on you if you stay in the car. 

    And Allaah is the Source of strength. May Allaah send 
    blessings and peace upon our Prophet Muhammad and his family and companions. 
    End quote. 

    Standing Committee for Academic Research and Issuing Fatwas.