From the article:

> In the U.S. you generally can’t just up and fire someone, even if they are underperforming, even if it’s at-will employment, without risking a lawsuit and some sort of cash outlay. This is what makes hiring decisions so high-stakes.

I've been part of a few situations where someone had to be let go in the USA, and I can tell you it wasn't a trivial decision. There were legal aspects, sure, but there was also a personal aspect. As a boss said once "this is someone's life we're talking about here".