The fact that you admit to being so "curious" to read people's personal medical files when these folks were at a damned rough point in their lives - just to prove your own personal point - is exactly why HIPAA laws were enacted - to keep people who have no connection with the person involved from rooting through their records.
Where I work I am the person who assembles the injury stats for peer-to-peer aggression, client-to-staff injuries, and staff-to-client injuries. Clients hurt staff the same way people hurt each other everywhere. Are you asking for a general idea of the types of injuries that staff incur?
Wait till you are trying to sew up the occasional large gashes that surprisingly strong whirlwind two-year-olds seem to attract and dealing with an understandably semi-hysterical parent with blood all over the place and your perspective might change. Hanging on to someone who is strong for their size and doesn't want your assistance and who is amazingly slippery due to being covered with blood does not make for graceful medical interventions. Similarly if your child doesn't understand that moving around may cause a bone that is setting properly to re-break and/or come out of alignment or pop a gastrostomy or G-tube out of place, these devices will quickly become an extremely helpful rehabilitation tool.
Anyone who wants to tie up or restrain someone does not need to wait for a set of properly adjusted well-fitting posey restraints. But if you have need (or frankly even if you don't) I would feel better about someone being restrained correctly and in the proper body alignment than I would with someone making something up from scratch.
Work a shift in an emergency room hospital with screaming, frantic, injured toddlers or with large adults who are totally unable to control themselves either due to psychosis, pain, or substance abuse. Think about things in context and how they can be properly used before assuming that these are items used for control and pain. ANYTHING can be made into an instrument of torture if that is what is in your mind and that is your intent. All that THIS is is an instrument or tool. The person who uses this is the one who has the ability to use or mis-use it.