You can answer this question from a more personal perspective to allow the interviewer to get to know you a bit better. Perhaps you looked up to your uncle who was a skilled truck driver, or maybe you enjoy being in the driver's seat. Talk to the interviewer about your passion for a driving-related career. As the interviewer knows, most of the time, people who genuinely love their jobs are great at it and perform consistently as model employees.
"Driving has always been a passion for me as it allows me to see and meet new people. I feel at ease driving passengers to their destinations. It is an enjoyable career, and I am grateful for the opportunity to be a taxi driver."
"After spending fifteen years on the road as a long-haul truck driver, I decided to look for a career that kept me closer to home but still incorporated driving for a living. Through research, I read how fulfilling a career as a taxi driver can be. This career change gives me the opportunity to dial down the amount of time I am away from my family. I can set my schedule for the most part, and still earn a good living."