It's not irreversible in any sense of that word.
First of all, you have a trial period of 3 to 6 months where you can fire someone without even giving a reason.
Second of all, you can have fixed-term contracts, like 1 or 2 years - also with the trial period.
Third, you can still fire people after the trial period, you just can't go Trump-yelling at someone "YOU'RE FIRED!!!" because of some small mistake or if you don't like their face. It's not an easy process, but also not impossible. I very much prefer it this way.
I'm seeing this at the company where a friend works. They have an american branch that completely changed the employee roster twice (!!!) in the last two years. Everything they do is a mess, every new person that comes brings a different point of view of how things should be done. In the end, they always end up falling back to implementing what their colleagues in Europe did. The europeans have been working together for 6 years now
PS: for my current job, where I have a permanent contract, the interview in-all took 55 minutes. About another 15 minutes of talking to HR on the phone and bam, here I am.