Makes for happy and productive workers, and also benefits companies who don't have to worry about loosing their best worker without notice.
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.