You need to be familiar with the legislation in order to understand your obligations and safety requirements. Legislation imposes penalties on individuals and organisations who, by their acts or omissions, put others at risk.
To fulfil legal and ethical obligations is one of the main aims of following the OHS legislation. Another good reasons for organisations to ensure that their workplace is a safe and healthy environment is $$$$$$. Accidents are very costly to an organisation. Read about the importance of making workplaces safer: https://www.safeworkaustralia.gov.au/making-workplaces-safer#logo