Does anyone from Australia know if casuals get paid overtime for working Sundays?

So a friend of mine doesn’t work Sundays but was asked to go in. He probably did the wrong thing because he didn’t go in without telling his boss, but told a work mate that he wasn’t going to which told his boss. The boss asked why he didn’t go in and he just said he forgot, so that’s when he said that ____ said he just wasn’t going to. That was when my friend asked him where the double time was and his boss laughed and said “oh it’s gonna be like that is it” and asked him to finish up today.