There's another fact I recently learned about the "tradition" of Australia Day on the 26th of January. The 26th has only been the official public holiday in all states and territories from 1994. Before then it was common for the public holiday to be on a Monday.
And even before that it has only been recognised as Australia Day since 1935. For a long time "Empire Day" was considered to be the national holiday. I'm sure there were many who were outraged that "Empire Day" was no longer being celebrated.