I think one of the possibly many reasons companies don’t hire seniors is this.
They are wise.
They are wise to all the tricks and manipulations bosses try to pull to make their employees work longer and harder for less, and all manner of degrading and belittling mind games that reduce employees to begging slaves.
Senior employees are not there to climb the ladder, so they don’t play those games. They’ve been there and done that a hundred times.
I think bosses are more interested in their own power than the good of the company.