I think in the majority of cases no one could reasonably expect that their manager is going to give them any heads up. In the vast majority of cases the manager is not going to want to deal with that. They will want it short and sweet at the end and then done with it. Unless you have some kind of really, really close relationship with your manager, you aren't going to get told ahead of time.
In addition to them just not wanting to deal with that a lot of them may be afraid you are going to stop working if you are told ahead or you might sabotage something while you still have access to oracle systems.
I would guess that HR directs managers to not tell their employees before the last day. I don't think that is particularly evil, it's just the way it's done. I have seen it done that way at other companies. I have never been anywhere where the layoff victims were given notice beforehand.
What does seem inhuman is the abrupt ending of health services on the day of termination. That's a real problem and Oracle should not be doing that.
Originally posted by @PcOQyiK-2pff. Wanted to reiterate this as, while we are all hurt and angry at the time of layoffs, it really does no good to blame managers for not notifying us in advance. I'm pretty sure they feel just as bad about the whole situation. It's not their decision, and many of them don't even know more than a day in advance who is getting let go.