Alternatively, if new employers were not paying a premium, they would have a harder time attracting talent, so they are willing to pay more to fill the slots th

Alternatively, if new employers were not paying a premium, they would have a harder time attracting talent, so they are willing to pay more to fill the slots they really need to fill. And employees have a switching cost, if you're getting paid 5% below market, that's probably not enough to get you to jump ship by itself.