Your friend might have been shocked because living in Los Angeles, a city known for its car-centric culture and sprawling urban layout, not driving can be somewhat uncommon or unexpected for someone your age. Many people in Los Angeles rely heavily on driving as their primary mode of transportation due to the city's limited public transportation system and vast geographic expanse.
Additionally, in many places, obtaining a driver's license and driving is often seen as a significant milestone and a standard part of growing up and becoming independent. So, when you mentioned that you don't drive, it might have been surprising to your friend, as it goes against the norm or what is commonly expected in a car-centric city like Los Angeles.
There could be various reasons why you don't drive, such as personal choice, environmental concerns, financial considerations, or simply not having a need for it due to living close to work or having access to other transportation options. However, keep in mind that not driving is not uncommon in some urban areas, and there are alternative transportation methods available in cities like Los Angeles, such as public transit, ride-sharing services, cycling, or walking.