If my next confession was that I had murdered, raped or tortured someone I would be immensely inclined to go. I’d want the chance to confess in my own church before handing myself in.
But remember, I think priests should break the seal only to stop future crimes. If a penitent admits that they are planning to harm themself or others they should be able to speak up. I don’t see how this wouldn’t stop people confessing.
As a note on mandatory reporting in the USA. Therapists are required to report if they suspect a specific minor is in danger of being sexually abused or has been sexually abused. So even if it’s a past event with little chance of repeat, US law would require the reporting.
Mandatory reporting of child abuse and neglect | Child Family Community Australia is a useful source which shows it seems to be the same in Australia. So normal mandatory reporting would include past offenses, not just belief of a future offense.
Now as to what you said, you first mentioned that you’d want to confess before
handing yourself in. Now to bring up one point, it is perfectly permissible for a priest to strongly recommend such a course of action. Getting handed in is another matter. And while it may seem ideal that a person would want to hand themself in, we’re broken. But we also have other life things in the way. Imagine, with your murder example, that the person is the breadwinner of their family. So if they go away, their family is now in danger of financial hardships. The kids also miss a parent as they grow up. Now it’s not just the penitent who is affected, but people they love for. Earlier you said you’d applaud the priest that went to hell to report child sexual abuse. Would you similarly laud the man that did so for his family to have means? (I’m trying to see this from your side and apologies if I get it wrong.)
And coming from my perspective, again the greatest goal is to get souls to Heaven. So if the Church has a way to offer God’s forgiveness to people so that they may be relieved of their sins, is it not right to do so? And in doing so, is it not best to make receiving God’s grace and His eternal gift as, probably a bad word choice here but it seems to fit, easy as possible? To put obstacles between a person and Christ that don’t need to exist is to deny them of God’s love. To deny them of everlasting life.
Part of what you’re saying, if I understand correctly, is that a person coming to Confession should be so wanting to be forgiven that civil penalties should not concern them. But that, to me, speaks to an “If you love God, wouldn’t you do X?” where ‘X’ is an increasing devotion.
Put in to every day usage, an example would be: You love God, so why are you listening to music instead of praying? Okay, now you’re praying, but why are you spending other free time reading that fun book instead of The Bible? Okay, now you’re using all your free time in prayer and Bible reading, but why not trim back on your sleep so you can do that more?
It is a burden between a person and Christ. And to put a burden like that, with the stakes at play, is a cruel thing to do.