Don't be so obtuse.
Of course legislation, codes of practice and regulations aren't going to specify a particular style of fencing. It is going to put forth the minimum requirements. It is then up to the relevant parties to agree on what meets those requirements.
Chief of those parties would be the company engaged to consult on the risk assessment process, and the company whose job it is to sign off and certify that the installation is compliant.
It's unusual that both Village and Dreamworld's new rollercoasters have much the same fences around their ride envelopes, no?
I wouldn't be surprised if they use the same companies for the risk assessments, and this is what that company has come back with.
I think in the current environment, and with the park's history - If the risk assessment they have paid for states a particular fence is required, and they choose to disregard that, it would be complete and corporate suicide.
If anyone wants a read, the relevant section is 7.3.1 - Access to an amusement device