What is extra freaky is that up around DC there are EZPass HOV lanes that have a toll UNLESS you have 4 passengers, then they are free. But there's no gate w/ a guy to get on it or anything... all done w/ cameras and machine vision to count bodies in a car.
That reminds me, I need to check my account out of curiosity, When we came down to NC a few weeks ago, when I went down that road, wife and both kids were asleep... slumped over pretty much invisible from outside.