It's mostly a tax issue. The operating costs of a Tesla can be much lower because of very favorable tax breaks, which is one of the main reasons the Tesla sold so well in Norway and The Netherlands (my home country), and why so many of them are fleet (lease) vehicles. Taxis alone account for a substantial fraction of all those sales.

We'll see if that trend continues in 2018, there have been some substantial changes in the taxes regarding electrical cars in NL, not sure about Norway.