Sitting in class, looking at an analysis that shows large households in mixed use developments generate more trips than smaller households, contrary to some expectations (not my own). I grew up in a suburb, and I was driven everywhere. While there are no stores within a half mile, there are a lot of retail destinations within a mile, including a regional mall. My neighborhood was bordered to the east and the south by five lane arterial roads (106th South and State Street). Crossing the street was extremely dangerous. Thinking back, I cannot recall EVER crossing these streets as an elementary school student (with or without parents).
I didn't start traveling alone until junior high. Almost all of which was along an abandoned railroad corridor, a canal path, and a residential street. I regularly crossed two arterial streets. Both had center turn lanes far from curb-cuts, and one was at a railroad crossing. Had those not existed...I may not have walked anywhere at all.
I'd hypothesize that more kids means more driving. Teenagers (especially in places with graduated licenses) are the primary suburban pedestrians. Anyone old enough to both have a license and a car drives. Suburban transit is commuter-centric: Long distance, peak-hour buses.