Contractual and lawful reasons.
You can’t be fired without proper cause so when they fire you without proper cause the wil have to keep you on board for a while or choose to pay you out for that amount of time. I was sort of a foreman with a teal of about 20 technicians and I also had to work directly with our customers. They deemed me a liability because I was fired so they chose to pay out.
Same with salesmen. When you fire them without proper cause they want you out of their network as soon as possible and won’t take the risk of letting you work with costumers anymore so they just pay out the amount of time that is needed.
This is about 20 years ago. Anyway, the absurdity of the situation still strikes me today. I was reading the newspaper provided by the company and mister manager was angry that I read something he didn’t like so he tried to force me into submission.