How does the 91 Freeway Express Lanes catch cheaters?

Q. Honk: On the 91 Express Lanes there are three-plus lanes that allow vehicles with three or more people to use the tollway for free, or at a significantly discounted toll. How do officials enforce those lanes? Do they have cameras or sensors complex enough to figure out how many people are in a vehicle, or is it more of an on-your-honor system?
– Peter Finch, Huntington Beach
A. It’s kinda like driving in a carpool lane solo when you aren’t supposed to.
We should just do the