I can't speak for other areas, but in Los Angeles, most of the senior editors are following the recommendation here https://www.waze.com/wiki/index.php/Car ... nsit_lanes
that HOV and Express Lanes be set to type Parking Lot Road until Waze has properly implemented some settings in the client, so that it knows the occupancy of the vehicle, whether or not the driver has a transponder for toll/express lanes that do not have toll plazas for payment, et cetera. Turn restrictions are also set not to direct drivers into the entrances for such lanes where they have separate ramps from other roads.
In answer to your question, yes, I believe that Waze thinks that users are in these lanes when they are not. The GPS tracking in the client is not accurate enough to tell whether a driver is in one of these lanes or in an immediately adjacent regular traffic lane, so if there is any kind of a gap in tracking, it may place you in the wrong lane when it regains a lock. Obviously, changing the road type of only an offramp from one of these lanes may not be enough in and of itself to solve the problem, but the more segments of these lanes which have penalties in the routing algorithm, the less likely the client is to route there.
In this case, it was a user reported map problem which brought my attention to the routing problem. The user's GPS track showed the vehicle exiting to the right, from regular traffic lanes, at the next available offramp. This suggests to me that he/she was not in the HOV lane.
Thank you for fixing that for me.