Just as the strata committee makes decisions as if it was the owners corporation, a delegated strata manager makes decisions as if he or she were the committee.
And, yes, in both cases, they are expected to observe strata laws and regulations and enforce by-laws.
There is a specific section of the Act (232 [2]) that deals with the failure of the committee or strata manager to fulfil their duties.
However, you have to seek mediation at Fair Trading before you can seek orders at NCAT, and simply initiating that process is often enough to get them moving.