An EV charging at night rate has very much less impact on the network than an electric heater running at peak. Presumably the EV tariff is all about ensuring EVs don't have an impact on the network by encouraging people to charge them overnight instead of just plugging straight in when they get home from work. I don't think the tariff will have the same appeal to those Briscoes heater buyers, they probably wont want to delay using them till 2am.
My point exactly. There's often people talking about the impact EVs have on the network with how much power they use, but an EV can, and often are charged off peak, a heater isn't. But you don't hear people complaining about someone buying another heater for their home and plugging it in!