I'm sure there are some people who are attentive enough about traffic before they start studying for a learner's permit (at 14 most places, I believe, not 16) t

I'm sure there are some people who are attentive enough about traffic before they start studying for a learner's permit (at 14 most places, I believe, not 16) to be described that way, but many are not. Especially if you live and go to school in a suburban area your experience with traffic is probably largely a) crossing not very busy streets, b) riding a bike on, again, not very busy streets where traffic laws are honestly barely obeyed anyways, and c) getting on a bus or being driven everywhere, at which point maybe you pay attention or maybe you don't. There's definitely going to be some osmosis but I think you're pretty vastly overstating it (and including several years in which your ability to even comprehend what traffic is is going to be severely limited).