Answer:
The taxi driver probably intervened due to his feelings of empathy.
Step-by-step explanation:
Empathy is the ability to "put oneself in another person's shoes". To completely understand them in a way that makes one feel for the other, to share feelings with others.
In this case, the taxi driver's empathy allowed him to connect with the individual's he thought were getting mugged and it pushed him to intervene and stop it, even though it turned out to be a performance in the end.