Lufthansa sues passenger for missing flight

This is what's called Point Of Sale (PoS). Flight price depends on PoS ie departure point. While within EU there is clear price parity I assume Norway is outside this so the same rule doesn't have to apply.

Sujit has it right but in this case the routing was more complex.

I think it was something like Oslo - Amsterdam - New York, then New York - Amsterdam - Berlin. The customer missed the Amsterdam-Berlin leg. And saved about 90%!! of what they would have charged.

I don't blame the guy - looks like the fares were absolute banditry by the airline.