Yes there are a number of laws prohibiting this.
The issue is not so much whether it is a strata complex, but rather whether the use of the garage as a hairdressing salon is an approved use. In other words, the garage would have council approval to be used as a garage, not a hairdressing salon.
There are quite serious consequences where someone uses a building or part of a building in breach of its approved use – it is illegal and there are a number of considerations that flow from that. In this case, it is probably more serious because the person is using the garage for commercial purposes. It is highly likely that the Council would not give approval for its use as a salon, as there would be a number of requirements it would have to meet. Even before that, the strata would have to give permission for any application for the owner to use the garage as a hairdressing salon and I doubt that they would do that.
In terms of the strata, if it is aware that an area within the scheme is being used contrary to its approved use, and does nothing about it, then it can be held liable as well. I suggest you contact the Council and seek urgent advice and then advise the strata manager that this needs to be stopped.