Yeah but ACC isn't even long term sickness leave. That would be a WINZ benefit e.g. Supported Living Payment.

ACC is specifically only for accidents. I can find an Australian equivalent to the WINZ support which works pretty much the same, but I can't find any info about salary replacement for what I think is the ACC equivalent, National Disability Insurance Scheme.

Anyway, I think we've decided there's no real study behind this "article", it's just a company trying to be talked about. There doesn't actually seem to be a study that we can read, and based on some of the other articles on their site (e.g. this similar one on work-life balance by US state) it's not very scientific. There's no source for the data they've used, and their choices of what criteria to use are pretty arbitrary.