About the enigma of patient trauma being "unavoidable": From a legal perspective, the occurrence of an injurious traumatic event does not, by itself, prove negligence. If the admitting nurse, in making an assessment by current standards, did not consider the patient to have been at risk of falling and there was no compelling reason for the nurse to be at the bedside at the time of the accident, then there cannot be a finding of negligence.
In short, the generally accepted standards of nursing practice do not require the hospital staff to observe all patients at all times. Such standards only require nurses to take reasonable precautions. Hence, the question is, "What is missing in the fall prevention protocol that has so many people plummeting unpredictably to the floor?" The answer is surveillance. The more surveillance there is, the less people will fall - simple logic. Consequently, the attitude of senior-level officials is of paramount importance. When you ask the obvious question "What assurance can you give me that my [mother, father, wife, husband, child, etc.] won't fall and get hurt?" the answer you need to look for is "Let's talk about things we can do together to prevent such a terrible thing from happening." If you do not get the opportunity for such dialogue, take control of safety and prevention by remaining at the bedside. You will then have to rely on your own judgment as to whether you can leave and for how long. You might elicit the help of other family members to take turns.