You mean the long rows of cars queueing one constantly see outside US schools aren't representative? I'd say it takes far longer to pick someone up in a car than a bike..
If you're in the US, it's likely that you either don't drive by schools when they're letting out, or you live in a place that has the right combination of density and poor kids to limit the driver pick-ups. None of the 5 places across 4 states where I've lived in the last 10 years have avoided the pickup line phenomenon.
You seem to have missed that this comment chain focused on daycare to begin with, not school. There's no bus for that.
Daycares vary in size. You can opt for institutions that watch after 30 kids at a time, or ones run out of houses, but one way or another if both you and your spouse work for a living, you need someone to watch your kid, and it will probably require daycare and by extension commuting. If you live in the suburbs, you drive.
