It was bungled... and “it was just their job” is another dog that won’t hunt either.
If there is a doubt that the person’s reservation will be honored... short of some wrongdoing by the person... then don’t let the person on the plane. Simple enough?
They understood that at the diner I went to the other day.
When involuntarily bumped, United is supposed to provide the passenger with written documentation of their rights and explain compensation. By law.
Yes, it takes time. Which is why it happens at the gate.
But they skipped those steps and went straight to "Rocco, Guido, Big Pauly, help that old doctor find the exit!"