You are right that Benedict didn't hold the bishops accountable. Is it because of the culture? Possibly.  I wonder, however, if it is simply that Benedict didn't get it. The whole time, Pope Benedict did not seem to grasp when people asked him about the scandal was that they wanted him to hold bishops accountable. Pope Francis talks like he understands this--but does not follow through with action. 

As for mandated reporting, aside from confession, in America, at least, in most, if not all states, priests are mandated reporters. Canon Law would defer to civil law on that--again, unless it involved Confession.