From the
NCDOT's
HOV page:
Welcome to the North Carolina Department of Transporation High Occupancy Vehicle (HOV) website. Here you will find information about the NCDOT HOV program and learn about HOV lanes. We are committed to providing citizens with opportunities to get involved in transportation decision making. Information is available on the various HOV projects around the state.
The central concept for HOV lanes is to move more people rather than more cars. Some HOV lanes carry almost half of the people carried on the entire freeway. Regular "mixed-flow" lanes are never converted to HOV lanes. Rather, HOV lanes are always added to existing facilities. [emphasis added] Each vehicle that travels on an HOV lane must carry the minimum number of people posted at the entrance signs. Usually that means at least two people, or in some cases three people. Each child counts as an occupant but pets do not. Violators are subject to a fine. Motorcycles, even those carrying just one person, are allowed to use the HOV lanes. Some HOV lanes are in operation only during certain hours, which are posted. Outside of those hours, they may be used by all vehicles.
Tell me it isn't like this in your state.