For our friends in Virginia - "Starting September 30, only hybrid plug-in electric vehicles will be allowed free access to HOV lanes without the requisite number of occupants" https://wjla.com/news/local/hov-lane-changes-hybrid-free
This is one of the risks of using special access privileges to use federally funded HOV lanes without being a true HOV. When the lanes start getting crowded and no longer flowing fast enough to meet federal guidelines, those non-HOVs are supposed to be ejected.
They were already limiting HOV access anyhow, long before this, and they also converted many of he old HOV roads to EZ-Pass. Because of this, I got rid of my "Special Fuel" plates and I have avoided the EZ-Pass tolls roads wherever possible.
Hm, I don't recall any special rules for plug-in hybrids in the past; I'd double check with the source (VDOT).
Up by me (NoVA), there is no HOV benefit for EV/PHEV/HEVs... even worse, the HOV lanes that were free to use off-peak are being slowly converted to HOT lanes. That means you either have 3 or more (HOV) or you have to pay a toll. The coup-de-grace is that VA doesn't get a lot of that toll revenue, it goes to TransUrban, an Australian company. So I have to pay the Aussies to drive on a road my taxes paid for and used to be free to use (off-peak)
Having spent more than half my career in a real carpool (Before Prius), I have no problem with this. But then, people here have adopted to all these new vehicles in fairly large numbers without incentives. Allowing them free access to the HOV / HOT lanes would immediately plug the lanes and destroy the congestion-busting purpose. And clobber the transit bus schedules.
There once was a time, back in the 80's, when public outrage at the tolls actually resulted in their removal. What happened?
The only toll removal I'm familiar with in my region is the old tolling on the original 520 floating bridge across Lake Washington. For some reason, the state kept collecting after the state's bonds were paid off, a violation of federal law in cases where the feds contributed a chunk of money too. A driver sued, won, and the tolls had to stop. More recently, I believe one of the HOT lane tolls was removed during off hours due to public feedback. But during the commuting day, they are back. But I'm not remembering any complete removal stemming from public outrage.
This is true in NoVA for I-95 and I-495 express lanes, however for I-66 inside the beltway the tolls go only to the State of Virginia. True, In NoVA soon I-395 and I-66 outside the beltway are being converted from HOV to toll lanes. So, no much HOV lanes are left. Maybe, a joke of HOV lane on Washington Street in Alexandria and an HOV lane on DTR which is already a toll road anyway. Do not confuse hybrid privileges in HOV lanes with HOT lanes. Never a hybrid was or will be excluded and avoid paying tolls in an HOT lane in NoVA.
Here it was by public consensus, but it may have also been as you state - the "violation of federal law" - that gave the public consensus teeth. Maintaining the tolls became a local hot button issue, and liability, with local politicians. As a result, they removed the tolls from at least one major expressway and two tunnels. Now the tolls have come back. They were re-installed at one of the the tunnels here, and another tunnel, that never had tolls, now has them. The expressway is still free, but they've converted most of the HOV routes to EZ-Pass.