Conveyor bed

[a bit of background, I’ll be brief] A month ago I came home late from work, about eight o-clock, to find my mom collapsed at the bottom of the stairs at the entrance to her suite and too weak to call for help. Turns out she was fighting pneumonia in both lungs, strep A, and Sepsis (a blood infection) culminating in respiratory distress syndrome. If I had worked another half an hour this story would have had a different ending. As it is, she was intubated and asleep for twenty one days but is now out of the ICU and causing the nurses all sorts of grief on the way to getting her strength back.

For several days after she woke up she was unable to move herself in bed, it is still quite a chore and the nurses have more important things to tend to than shuffling people around in their beds to find the most comfortable position or to help the patient sit up at whim.
The beds themselves are adjustable but if someone has slid down, changing the bed to a sitting position does little besides cramming a patients' chin into their chest.
So, short story long, why not have conveyor hospital beds?
Waterproof detachable fabric, the width of the bed, would be stretched taut over rollers at the headboard and footboard allowing the patient to control their own positioning with the push of a button.