Auslan is a visual language and Australia is a big country. Before the development of technologies like video chat there was no way to share the language with people you could not physically meet. So the language evolved uniquely in different parts of Australia.
There is no part of Auslan where this prevalence of different signs restricted to region still remains as strong as it does with colours.
This is a bit like the English words Swimmers, bathers and togs They all mean the same thing, and it does not matter which you prefer. However just like this example, sometimes there is a stronger preference based on region.
