Just because it's physically possible doesn't mean it's plausible.
You're driving through the neighourbood at 10am in the morning, you take your eye off the road for a second, or someone walks out of a blindspot. You knock them down.
Do you...
a) take responsibility, check the victim and call for help
b) panic and quickly drive away, leaving the victim behind
c) get out, drag the body into your vehicle, hope no one saw you in the middle of the street. Now you go and dump the body and face possible murder charges?
People's natural reaction is going to almost always be either a or b. I also suspect that someone would've heard or seen something had there been a road accident, since Jason's journey took him through the street on his way to the school.
Btw, I doubt Jason was "taken off the street" so much as lured by someone he knew. I tend to believe he either got into a car or entered someone's home shortly after taking in the trash.