Which is what makes it hard for you to fathom it doesn't have to be that way you experience. When my company laid of half it workforce two years ago, everyone stayed for a few weeks to help in the transition, with the same accesses as before. Because we were treated nice all the years working there, and with respect during the process, it was absolutely no ill feelings or any risks of people doing what you describe.
So again, please read and answer comments in good faith. It's your mind that's not open enough for alternatives here, please bear that in mind - don't use your own closed mindedness to misread my comments.
Edit: your other comments in this thread shows you absolutely loathe your employers. I feel sorry for you having had those experiences, but don't assume they're global.