DS is 18 months old and since the day we left the hospital I've sat in the backseat right next to him to keep him company. DH works 8-430 every week day and I don't drive anywhere unless my mom comes with and sits in back or she drives and I'm in my normal spot in the back. When he was a baby I did it because he fussed by himself, even with a mirror to see us up front, so i just started staying in back and it's never changed. Trust me there's times Id love to go somewhere during the day just him and i, but I have yet to do so because he even hates getting IN the carseat, so I'd have to calm him down before getting up front to drive somewhere. So far I've been ok with hangin out at home til DH is off and we run out errands. It's a family thing anyways, running errands.
BUT I know he CAN sit back there alone for short drives because he's done it before on three occasions where I had a doc appointment and DH drove him down the road to a Walmart to walk around until I was done. Also, I breastfeed him in the carseat when he's extremely fussy/
EDIT: I posted this not even 2 days ago and already had 140 responses by this AM, so I'm honesty not gonna read through the next 200 comments because I know now that I am the ONlY one who does this, that I am hindering him more then helping him, and that I need to change this NOW. So thanks to the moms who told me this NICELY and screw off to the women who were jerks about it.