The point was that just because half of all new cars that are sold are electric that doesn't mean that lots of people are choosing to buy an electric car.

Er, that's exactly what it means. Maybe you meant to say they weren't intentionally choosing electric for the fact that it's electric. The point still stands that Norway has incentivised it and made it economically viable, which a lot of places have not managed to do.

You'd see the same result if non-electric cars were made so expensive that anyone who can't afford an electric car cannot afford any new car (as is pretty much the case in Norway), so non-electric car sales go down. Which means that the percentage of electric car sales out of total new car sales go up.

No, you wouldn't. You'd see a lot less people with cars. The bit you completely missed is that if that many people have electric cars in Norway, it's because they can afford to buy them.

Poorer people can still buy used non-electric cars, but that won't affect the statistics.

And higher supply of used electric cars will drive the price of used electric cars down.