The Yes campaign did a poor job of selling the change to most Aussies. Also, given that they, like many others around the world right now, are going through a cost of living crisis the timing of this wasn't great. Many voters have more important things to worry about.
The No campaign kept it simple with the slogan of "If you don't know, vote No". It worked.
Also, implying that someone who is planning to vote No is uneducated, or a racist, probably wasn't the best way to go about persuading them to change their minds.
Finally, I know quite a few Aussies who are neither uneducated nor racists. They have told me many reasons why the people in question aren't entirely blameless where their current situation is concerned. Maybe you should do a bit of research and find out what goes on in some remote Australian communities? It might help you understand why the majority of Aussies aren't that sympathetic to their plight.