They start at a lower amount and then increase it until they have the required people. The lower and upper bound on what they can offer first appeared in a leaked 2017 memo. 2017 also happens to be the year of the violent removal of someone on a United flight: https://en.wikipedia.org/wiki/2017_United_Express_passenger_...
My guess would be that Delta put this policy into place after the terrible United incident.
My guess would be that Delta put this policy into place after the terrible United incident.