Are you suggesting that it's bullshit? I'm not buying that (not til the afternoon when it's cheaper, anyway)If it's that much of a monopoly (like, it's one road in and one road out) then surely they can charge what they want permanently on either side? Why faff around.
And how have these Norwegian folk not copped on to do a bit of a round trip and fill up on the other side one day? You'd only need to turn around wherever you can, first roundabout or whatever.