Hazing exists within the system - there is no person at Michigan who can reasonably and honestly deny it. Obviously, it does not exist in every group, there are some groups that are much, much worse than others. In terms of physical hazing, it is almost certainly much more prevalent in fraternities than sororities.
It can vary from “low-risk” like just pressured medium-heavy drinking, doing a lot of embarrassing odd stuff (like make sure you wear this specific pair of shoes and do not ever be seen without them) to much more “high risk”. Michigan Greek Life is certainly not as toxic as a school like Penn State’s however. I had plenty of Greek and non-Greek friends in school.