Of course you can still be fired instantly for huge mistakes but it’s difficult to prove for them which is why I’ve never seen it used.
I have seen it a few times, but there have to be severe and generally repeated offenses, though you can get fired instantly for stuff like serious stealing from the company. But then again, there was once a dude who tried to start a fist fight with his bosses’ boss, which apparently wasn’t enough for him to get fired instantly.