This extended warranty thing is common throughout the EU (in the UK it's 6 years for example). In the UK we pay more than the US for most things but it's hard to pin down the exact reasons and price differences.
In the last couple of years the Sale of Goods Act protections were weakened as part of bringing us into line with Europe. It's now been replaced by the Consumer Rights Act which although clearer gives fewer rights to refund from the seller.
Note it's the retailer rather than manufacturer who is liable, so we have much more confidence that what we buy is "of merchantable quality", safe and legal to sell. Quite a number of HN threads have made this advantage clear.
No, they seem to about comparable i think.
Electronics is generally ok priced here.
I have no idea about apple prices in general, but a "Apple iPhone 6s Plus 128GB Sølv (Silver)" is approx 1257 USD including 25% VAT.
That is about 1/3 of an average monthly salary here, maybe a bit less.
For comparison: it's $949 + sales tax in the US, and 1075€ ($1200) in Germany, including 19% VAT. So the German price without VAT is the same as the Norwegian without VAT.
Mandatory warranty in Germany is 2 years, where in the first six months the manufacturer has to prove that it wasn't defective when they sold it to you if they want to dispute your claim. After six months, there's a reversal in the burden of proof, but claims are usually accepted without dispute. I'm not aware of anything that requires more than two years of warranty here, even for durable goods expected to last longer than that.
Just nitpicking: the mandatory warranty ("Gewährleistung") is supplied by the seller, not the manufacturer. As a consumer you don't need to deal with the latter no matter what the former is trying to tell you. In the same line, the burden of proof after six month is on the seller not the manufacturer.
A manufacturer often has an additional voluntary warranty ("Garantie") distinct from that.
That is the case (including the role of the seller) across the whole EU by Directive 1999/44/EC (although member states can go beyond that and often do by e.g. extending the time).
It is the same here, you never deal with the company, just send it to the store and they handle it from there.
The five or two year warranty is called "Reklamasjonsrett" in Norwegian which covers design and manufacturing flaws.
It also states that the seller can try to fix it three times, after that it needs to give you something equivalent (i.e. a new phone of at least the price of the old) and that they can't charge the customer for any ting relating to the repair.
But we also have the "Garanti" from the manufacturer like you do.