The above is definitely correct in the sense that neither Legal Studies nor Business Studies are treated as prerequisites/assumed knowledge for relevant university degrees.
My understanding is that taking Legal Studies is not required if the sole intention of taking this subject is gaining foundational knowledge of law before studying a Bachelor of Laws. However, it does provide you with insight into law, including the Australian legal system, which constitutes a nice addition to your general knowledge and can potentially assist you with the start of your university journey (for example, during your first semester).
Business Studies is more interesting because it is a multifaceted subject and so is a degree like a Bachelor of Business/Commerce. In the Business Studies HSC course, four areas of business are covered, being operations, marketing, finance and human resources, all of which can be explored further at undergraduate and/or postgraduate level. This of course means that Business Studies content is relevant to content studied at university for the particular field that you wish to specialise in. In the case of marketing, concepts that are revisited at first-year level include the marketing mix and situational analysis (including SWOT analysis). Concepts relevant to marketing that you will learn for the first time alongside those that you would have already explored include the 4 P's of innovation as well as the marketing environment. The relevance to other areas such as human resources is also evident given that there are subjects that explore concepts such as development and performance management in more depth, but I will not go into those further here since they are not relevant to your study interests.
Additionally, Business Studies briefly covers components relevant to economics, such as exchange rates. While the knowledge that you would gain from taking Economics would be sufficient if you wish to study a Bachelor of Economics (or similar), taking Business Studies alongside Economics could maximise your knowledge of this field before studying this degree.
Of course, if you are interested in English Extension 1 and/or Visual Arts, then those should be prioritised, as you will not be at a disadvantage if you don't take Legal Studies or Business Studies.
I hope this helps!