As soon as the government decided to sell permits for one person usage of the HOV lanes, the game was up. Enforcement is generously described as spotty,
It's an honour system, pure and simple. It was naive to create a road policy that would rely on police officers making very risky traffic stops for a non-critical infraction.
If the officer sees unsafe behaviour, such as improper lane changes into/out of the HOV lane (I see many motorists who use it as a high speed passing lane, crossing the solid white lines freely) or excessive speed (some people think the HOV lane allows higher speeds) - then I would expect they would see good reason to pull over the offender, and not having a second passenger is an additional offence that can be cited.... gravy for the court.
But pulling a car onto the left shoulder, into the narrow space against the center barrier, where there has been no adverse safety consequence, is not a good idea, and I'm sure that the OPP have bigger fish to fry.