Moving to the UK from Norway was a shock to me in the sheer length of employment contracts. Prior to that most of my contracts had been a single page: Norwegian law regulates default terms so strictly that long contracts are rarely needed. In fact, they are hard to make enforceable, because any additional concession to the employer needs to be justified, usually by extra consideration. But many rights are inalienable.

It's a recognition that few employer-employee relationship approaches a negotiation between equals.