As most things in school, it's an artificial situation that bears no resemblance to the real world.

IRL:

- people has much higher stakes, while in school tanking a class project is no big deal for most slackers. IRL, they can get excluded, isolated, shamed, fired and so on.

- such group would exist rarely in the first place, because institutions filter people;

- if you are in the rare situation it happens, you can get out of it, but you it's very hard to move in the school structure, not to mention out of it.

Anecdotally, I've seen the scenario playing out many times in schools, but rarely in a restaurant, a dev team, a NGO or a sport club. There are productivity differences, sometimes immense, and an occasional slacker, but that's not the same order of magnitude at all.

I've seen the same school-type dynamic play out in companies amongst people getting paid the sort of numbers that make folks on HN say "most people don't get that, not everybody works at a FAANG."

We (as a species, really) are bad at interviewing lots of people that we don't already know well - just like we're bad at testing academically, surprise! - and we're also bad at coaching/firing/managing them.