The less said about PHEVs the better - utter waste of time, and people who drive them think they have a real electric car! It brings out the worst in me when someone mentions PHEVs!
As for other EVs using free chargers - let them, as long as they are actually using them! Normal etiquette applies. Usually I see cars like Leafs and Zoes charging from them - cars that can't get a rapid charge elsewhere, and they might only have street parking at home so that's their normal charge spot. I never need to use them as I do my normal charge at home, and if I am travelling somewhere, there's always a supercharger in range.
As for other EVs using free chargers - let them, as long as they are actually using them! Normal etiquette applies. Usually I see cars like Leafs and Zoes charging from them - cars that can't get a rapid charge elsewhere, and they might only have street parking at home so that's their normal charge spot. I never need to use them as I do my normal charge at home, and if I am travelling somewhere, there's always a supercharger in range.