It's a very good question.
The reason some jurisdictions in Australia do have a reverse onus.... Where the reverse onus appears, it usually appears in relation to the criminal offence of reprisal and proving that. Many of us don't focus on that because it's almost impossible to prove criminal reprisals in any circumstances anyway. Also, criminalized reprisals are a distraction from the real issue, which is achieving remedies for people who suffer adverse outcomes from all the things that are not deliberate and not criminal, but are detrimental actions, both acts and omissions, deliberate and undeliberate.
When it comes to the broader test of liability or if an entitlement to remedies is raised, generally speaking in Australia, the wording is very broad. If there was any detrimental action and there was a public interest disclosure involved, then the language is already very broad to say that the detrimental action is compensable, so that it doesn't have to deteriorate into the question of proving that there was any detriment or that the detriment was caused by intention to cause a reprisal.
That's one reason why it's been less of a focus here. The thresholds would be automatically more liberal, but that doesn't mean that it hasn't been a problem and there are some quite strong views that there needs to be a clearer reversal of that onus.
I guess the reason why I don't focus on it so much is that it really is a question that arises in relation to that criminal or disciplinary liability for reprisals. In my view, that's substantially a distraction from the main gain, which is making sure that civil remedies are available.