I wouldn't be surprised if battery heaters are mandatory up there. I think in the colder parts of the states (Minnesota, Maine, ND, etc.) there are plugs along parking spaces in cities and towns so people can plug in their cars to keep the engine heated while they are doing whatever they need to be doing. I personally have no desire to live in such a place, or even go up there to check if that is true. I lived in northern Ohio for years and that was cold enough for me.
We bought our Leaf in 2013 when gas was over $4/gallon and I thought that was going to stay like that. I was wrong, but it is probably inevitable that it will get there again and probably stay there this time.
If that $7500 was a straight rebate instead of a tax incentive the Clarity would be just as much in demand here. Most people hear incentive, don't know what that means but knows it is another tax form to fill out, and that is enough for them to stop listening and look at something else.