Being 'fair' helps company relationships with current and future employees.

Does it though? In my experience any "credit" for fair behaviour disappears very fast. Employees don't really care about fairness, they care about themselves here and now.

Equally businesses see employees as disposable, and work to maximise short term profit, not fairness. There's generally a lack of trust in one, or both sides, and that results in poor behaviour from both sides that spirals.

Sure there are great companies to work for, but all their greatness is tossed aside as soon as a better offer comes along. Employees look out for #1. Employers do the same.

People generally like long-term stability and are willing to trade their loyalty in exchange for that, even to the point of turning down a more lucrative offer. Back when companies appreciated that, you had plenty of people with a stable employment at the same company for literally decades. But then this cycle was broken when employers started to treat their employees as disposable (all while still demanding at least token loyalty!) in pursuit of more profits - and they have succeeded in teaching the employees that any talk of loyalty from a business is virtually guaranteed to be a scam, so why would the latter ever take it seriously?

In short, this is not a "both sides" problem.

One would like to hope that some of these companies act in a manner that when the shoe is on the other foot, and it is an employees market again, that they will be judged by their actions.