As the discussion has polarised to a contractor v permanent one, I would ask why does anyone think that Norwegian use the former model. Is it not for their benefit ? Does it not allow them to hide away from decades of employee protection legislation ? Who pays (in UK) NI employee and employer contributions ?
Mr GF has a good point. There may or may not be examples of inappropriate contract non renewal, those on the outside cannot know, but the fact does remain the opportunity for the employer to abuse exists and this is what employment legislation is there to protect against.