Catholicism is much older than Protestantism. Given enough time, corruption grows in organizations. As far as child abuse goes, it was easier to sue the Catholic Church than other organizations because it was one big established group. However, if you look at schools, sport teams - there is a lot of child abuse but these are smaller groups to sue (think of Penn State). When you are young, being your own church doesn't work out very well. You need to learn things externally.