Alternate energy vehicles, as well as other alternate energy measures as a whole like PV (photo-voltaic solar panels for homes), cost what they cost. If everyone had electric cars only, the prices would be in line with internal combustion engines, and there would be charging stations at every-other space to charge your car's batteries.
Until then, accommodations and "perks" are intended to incentivize people to switch to electric vehicles. Hawaii has a goal of reducing our dependence on oil imports as close to zero as we can. That includes electricity generation which is needed to recharge electric vehicles. The federal and state governments were giving tax incentives to offset the extra cost of electric vehicles so the sticker price is closer to a comparable gas vehicle. Once a make/model meets a certain number of units sold, the incentive goes away.
If you support the efforts to try and improve our CO2/climate change impact on the environment, then the cost to incentivize alternate energy source use is insignificant. If you don't care about that, then not being crushed by gas prices in the islands every time a crisis causes close to $5/gallon prices at the pump might persuade you to drive either an electric or hybrid vehicle.
I bought my daughter a new Prius almost 7 years ago just before gas prices spiked again. Luckily, we were car shopping before the spike. When we picked hers up at the dealer, the salesman said all Prius models were sold out in the week after we paid for hers. When gas prices are high, it doesn't take long before the electric/hybrid car pays its sticker premium through savings in gas. When gas prices are low, you might break even about 6-8 years after purchase. She finished paying off the loan when she graduated college, and she's loved her car. It has not only hybrid gas/battery mode, it also has an EV (Electric Vehicle) mode. If the battery is charged enough, and you keep the speed below 20-30 MPH, you can drive in EV mode just like an all-electric car.
Everything in Hawaii is expensive. Alternate energy cars are no exception. I don't think only "well-off" residents benefit from alternate energy technology -- unless you're thinking about Tesla. That's a whole other conversation that irks me! They are the Solyndra of electric vehicle companies.
