Because they can. Because job openings are scarce enough that people are applying anyway, regardless of being treated like shit. That's why we tolerate "but we're scared of lawsuits" as a legitimate excuse.
This sort of thing (and hundreds of other similar phenomena) doesn't show up in unemployment metrics, but in a healthier economy, it doesn't happen as much, because people dislike working for assholes.
It's a bit like how an Australian 5% unemployment (at $12.30 minimum wage) is very different from an American 5% unemployment (at $7.25 minimum wage) or a North Korean 5% unemployment (making $0.40 at Kaesong); The supply demand curve on employment is real, but it extends beyond tangible quantities like wages and into ways the employer behaves towards its employees & potential employees, because for workers, civil treatment is to some extent fungible with wages. In the US, we have much less labor regulation and more lawsuits, and this is the equilibrium we have arrived at in the current economic climate; In a different economic climate, we would arrive at a different equilibrium.
The official understanding of the problem is plagued by Goodhart's Law - you can measure wages, but not being an asshole, so we will favor policies which push on one but ignore the other, and we can expect assinine behavior wherever there is even a little bit of profit to be gained; We sample and optimize "Unemployment", "Inflation", and corporate revenue growth as indicators of the economy's health, and a lot of other things have fallen by the wayside as we have reassured ourselves or worried ourselves with those numbers.
This sort of thing (and hundreds of other similar phenomena) doesn't show up in unemployment metrics, but in a healthier economy, it doesn't happen as much, because people dislike working for assholes.
It's a bit like how an Australian 5% unemployment (at $12.30 minimum wage) is very different from an American 5% unemployment (at $7.25 minimum wage) or a North Korean 5% unemployment (making $0.40 at Kaesong); The supply demand curve on employment is real, but it extends beyond tangible quantities like wages and into ways the employer behaves towards its employees & potential employees, because for workers, civil treatment is to some extent fungible with wages. In the US, we have much less labor regulation and more lawsuits, and this is the equilibrium we have arrived at in the current economic climate; In a different economic climate, we would arrive at a different equilibrium.
The official understanding of the problem is plagued by Goodhart's Law - you can measure wages, but not being an asshole, so we will favor policies which push on one but ignore the other, and we can expect assinine behavior wherever there is even a little bit of profit to be gained; We sample and optimize "Unemployment", "Inflation", and corporate revenue growth as indicators of the economy's health, and a lot of other things have fallen by the wayside as we have reassured ourselves or worried ourselves with those numbers.