This is not a general privacy law for every private business in Western Australia. It is mainly a public-sector privacy and responsible information-sharing framework. The reason it belongs in a small-business library is that many small providers sell into government, support public programs, process applications, host systems or analyse information for WA public entities.
When that happens, the legal obligation often arrives through the contract. The customer may require strict controls for personal information, government information, information-sharing agreements, breach reporting and data security.