I really think the Carpool violation fine should be something like $10,000. Something insane.
It pisses me off watching the cheaters when I'm stuck in traffic. The fine just isn't detrimental enough (and it's not a moving violation on your record) for people that make decent money not to exploit it.
Or allow PAY-PER-Carpool, type lanes. We have a few in WA, actually.
I also don't think Mom's should be allowed to use their 2 year old as "Carpool relevant occupants". It should ONLY be people with a Drivers License (Or old enough to have one). It's not like that 2 year old urgently needs to get anywhere.