My mom and dad have both bike commuted in their time. Mom had a pretty scary encounter with me (as a toddler) on a kid's seat in the back. A motorist ran her onto the curb and we crashed in the grass.
My dad commuted daily 15+ miles one way...and the worst he encountered was having to change a tire on the side of the road in a known drug market...while wearing spandex.

I think my folks still worry...but they loved their bikes...so they wouldn't try to keep me from it. But I can totally understand kow those that don't know the sport let their knowledge of traffic lead them to fear it, and call it extreme.