Usually hospitals want to keep you to make more money.
That’s just it. If she was poor, the hospital wasn’t making any money on her.
These days, hospitals push people out early to free up beds for the next patients.
If you try to insist on staying in the hospital, they’ll make things very uncomfortable, for example yelling at you to get out. Try arguing with them, and they will call security.
It’s amazing that what happened to this poor woman doesn’t happen to more people.