When you use your car’s built-in speakerphone feature, the speakers in the car door reverberate, sending the sounds outside of the car. Maybe don’t do this while your car is parked. Everyone in the neighborhood or store parking lot can hear your very intimate or business-related conversation.
That makes sense. It didn’t even cross my mind that someone would connect their phone to their car’s audio system specifically to take a call unless they were driving, lol
You probably didn’t think of it because you’re not a lobotomized degenerate.