One factor is that the price of gas is about $1.6/L (~$6/gallon), while electricity still is very cheap. Most people also don't generally need to drive all that far, so a shorter-range electric car is perfect for daily driving. There are TONS of Nissan Leafs out here in the suburbs where I live. In 2018 the Nissan Leaf was the most sold car in Norway.
Buying an electric car in Norway also gives you much more than just tax savings (but they do have a lot of those). You don't have to pay road tolls, you can use the highway lane reserved for taxis and busses, you can park and charge for free in government provided parking spaces, you have 50% off tickets for ferries, cheaper mandatory yearly road insurance, and some shopping centres previously had free charging while you shop.
The right to drive in the bus-lanes was changed to only with at least one passenger during rush-hour, as they became so clogged that busses were stuck in traffic as well. The free road toll will be changed to 50% off this year, and the exemption from sales-tax is up for review in 2020. The free charging on government provided parking will be limited to 4 hours this year, and a fee per hour will be introduced. You can still park for free though, but those spots with charging stations are too popular.
Could be, but given the much larger influence that the state oil company Equinor (previously Statoil) exerts on the government, I'd not think it's likely.
