Means you're unlikely to get another job in the industry.
>bullying a leaver for all of 3 months to discourage other people
Would result in an easy case for constructive dismissal.
And then there probably is a way to shorten the notice period when both sides agree (I extrapolate to Norway how in my country it works).
I get that it's apparently an employee protection but it does seem kind of ludicrous. What happens if you rage quit? Win the lottery?
Well, I'm a professional, so I finish my job...
I shouldn't be changing job more than once every 2 years, so 3 months is nothing. The notice period is often reduced for the first 6 months, or you can ask for that before signing your contract.
In reality a company has no real desire to keep a disgruntled employee longer than they have to, so you can burn bridges and leave earlier if force the issue. It's a pretty unprofessional thing to do though.
Makes for happy and productive workers, and also benefits companies who don't have to worry about loosing their best worker without notice.