Since I ride my motorcycle to work (and seem to go a bit faster than anyone else in a cage), I get to peer into the cars of all those folks who drive in the carpool lane.
I wish I was surprised at how many of these carpool lane users don't meet the minimum two-people-to-a-car threshold. It's as if they think they need to get where they're going so much earlier than you solo drivers do.
Now, I've gotten quite good at spotting the tell-tale signs of a child seat that brings a frazzled parent up to the carpool-lane worthy status of shortening one's trip during commute hours. So they qualify. When I've taken one of my daughters with me in the carpool lane (in my car, thankyouverymuch), I've gotten quite the nasty glares from those who don't see the kiddie seat in back and assume I'm a member of the solo-drivers-better-than-thou club.
Now, many folks don't see the difference between the above two classes of commuters (solo parent with toddler in the back and solo-driver, period), and they don't hold back their contempt for the parents-with-toddlers "clogging up the carpool lane." (You can watch for their whining words to cycle the Merc's Mr Roadshow column every month or so)
Given that, I'd be very interested to see how many of these rabid "it doesn't count as a carpool if it's just a kid in the car with you" folks are also firmly in the "pro-Life" camp. My guess is, there's quite a bit of overlap.
If anyone can get me the data, I'm happy to make the venn diagram. I'll even make it in the colors of your choice!