Grounds for suspicion

The offence requires a substantial risk existing, knowing of the risk, being in a position with power and responsibility to reduce or remove the risk and negligently failing to do so, that is, "falling short of the standard of care that a reasonable person would exercise in the circumstances."

http://classic.austlii.edu.au/au/legis/vic/consol_act/ca195882/s49o.html

That seems a pretty good codification of the crimes that George Pell and his colleagues have been accused of but have not been charged with.

Does recent codification of the offence preclude charges based on crimes committed before the codification?

In what barbaric society has it ever not been a crime for people responsiible for taking care of children to neglect protecting them? Has the moral panic about child sexual abuse obliterated memory of the mandatory protection of children from harm in general that predates civilization and has nothing to do with either sex or police? "Little Children are Sacred".

George Pell was convicted of raping two children because nobody from the Church he leads has been charged with notorious crimes of failing to protect children.

Retribution is an important element of criminal law enforcement quite separate from deterrence and rehabilitation. If you allow impunity for notorious crimes you can expect far worse than unsafe prosecutions on some pretext or other. Sacrifice of scapegoats may or may not catch a guilty scapegoat. But its most likely result is to satisfy the instinct for retribution while letting criminals escape justice.

Historically children complaining of abuse have often not been believed, not only by priests, and especially when the complaints are made decades after the event. That has made it necessary to relax rules of evidence regarding corroboration, tendency evidence and joint trials and to instruct juries that it is not uncommon for an adult to come forward with a complaint decades after the event and to be inconsistent about the details.

There was a history of police collaboration with authorities accused of child abuse, especially catholic police with church authorities. That had to be reversed by training police as well as social workers to side with and believe the accuser.

These changes are intended to increase the proportion of successful convictions and necessarily create a very real danger of wrongful convictions. There are good reasons for the opposite policies to be followed for most serious crimes. We prefer to risk guilty people being acquitted than innocent people being convicted.

The exception that has been made for child sexual abuse puts a heavy onus on prosecution authorities to determine whether a prosecution would be unsafe. They can make that decision more objectively at a distance. Police and social workers can still comfort and side with the victim despite the prosecutor's decision not to put both accused and accuser through a trial that should, if it results in a conviction, ultimately be overturned as unsafe on appeal.

The alternative of putting every accusation before a jury that police trained to believe accusations find credible, would inevitably result in unsafe convictions.