"Sorry Day" is an attempt to get the general population to think about this, and to not necessarily apologise personally, but to feel sorry that it happened, and to acknowledge that it was a terrible thing to do.
Of course, there are bogans who think they have have nothing to say sorry about because they didn't do it. If you were to say to them "Jeez mate, I know you crashed your car but I'm not sorry because I didn't do it, and none of my family did it" they would think you're a bastard.
I'm sorry the government of the day took children away from their families. It should never have happened. I'm sorry Aborigines weren't even counted as citizens until 1960. But most of all, I'm sorry there are bogans who are not sorry.