> When I was young my dad used to bike me to daycare/school all the time.

How did all your siblings fit? Or did your Dad make multiple trips?

> live within a 15-20 mile radius of work

You really think people want to bike 20 miles? That's going to cost you about 2,000 calories (round trip). That's completely unrealistic for most people. They would have to double their food, plus end up exhausted every day at work.

And that's for perfectly flat terrain!

(The weirdest part is the extra food costs more than the equivalent gasoline, and produces more CO2.)