Because it took over 50 years for the Horror to be brought to light, and in the rarified club of the Clergy most of them all knew for years and did nothing.
The victims were abused for years and are still being abused by the likes of cardinal Phoney Mahoney.
Cardinal Ratzinger would have received all the reports of abuse from all the bishops around the world and he let the children continue and left the Criminal Priests in place to do more damage.
He allowed, the Leader of the Legionaries of Christ, Father Dogollado to avoid being challenged even though there was 9 men with credible sexual abuse allegations filed against him by lawyers in the Vatican.
Ratzinger (Benedict) is a European, and it doesn't appear (from the latest sexual abuse charges levelled against 25 Italian priests) that these charges are taken quite as seriously in Europe as they are in the States.
In fact, Ratzinger's first comment on the subject, in 2002, was to rebuke the press for making such a big deal of the accusations, when they involved so few priests!
John Paul II basically ignored the charges because 1) he had no idea how to handle them and 2) to accuse someone of homosexuality in Poland was the way communists discredited them. So he had a knee-jerk reaction against those making the accusations.
Cardinal Ratzinger preferred to let the American bishops handle them. Unfortunately, Catholic dioceses will be bled dry economically because bishops didn't remove abusive priests until they did a great deal of damage.
It's a painful lesson for the hierarchy and those in Rome to have to learn. Hopefully, they will learn it, but it does appear the Italian bishops are insistent on learning all about it through experience.