Covering confession under mandatory reporting rules would have little effect even if priests did report. Few would confess such a sin if they thought their confidences were not secure. Many pedophiles, anyway, are so delusional that they do not think what they are doing is wrong, and therefore do not confess.
Finally, it’s not often that a priest can identify who is confessing to him. A penitent could find a priest who does not know him and confess in a confessional box where there is an opaque screen between him and the priest, which would ensure anonymity.