After 25 years in healthcare, I believe most patients experience misadventures. Most are trivial, e.g. aspirin 2 hours late. But incidents are more frequent than the public imagines. And can cause serious injuries. For the sake of this article, I will agree.
Systems can set up caregivers.
In terms of rates, as an insider, I had access to incident rates for several hospital systems. In the 1980's, some hospitals reported rates of 9 events per 100 patient days. While that may sound like a low rate, it is actually high when compared to other hospitals that reported a rate of 2.5 incidents per 100 days in the same time period. A review of the four-fold difference in rates revealed that the difference was a difference in the rate of reporting, not the rate of incidents, and a difference in definition. Caregivers do not report their errors any more enthusiastically than other people do.