It’s on the list, but not likely to be something available any time soon - as it’s complex. Which is why I suspect the Manager team hasn’t implemented it yet - their goal is to appeal to a wide audience, a worldwide audience. Spending 50+ hours on a solution that will only benefit Australians probably doesn’t make financial sense for them.
Instead, have a look at this list supplied by the ATO for free and low-cost STP providers:
You can always use a payroll system that supports STP to store detailed information, whilst keeping basic payroll data in Manager at the same time to meet tax obligations.
For example, that is what a moderator has suggested here: