Is hitting a taxi driver for some sin an act that requires expiation?

The driver's misconduct in refusing to transport you or canceling the trip does not justify your hitting him. You have clearly wronged him. You must repent to Allah, and part of your repentance is to enable the driver to seek retribution (qisas) or to seek his forgiveness for the wrong you inflicted upon him. If you are unable to do so, then humbly implore Allah to satisfy him concerning your wrongdoing on the Day of Resurrection, increase your prayers for his forgiveness, and follow this bad deed with good deeds that are equivalent to it.