I also disagree with the way you phrased your point, on one hand, you mention that the unions would not budge on conditions, but then state that they should have because "no other company that you know of" allows 21 days of holiday over the Christmas. First of all drawing to the fact that the Union represents workers, not companies, it makes sense why the companies have an interest in shortening the holiday break of the workers. It is not in the interest of workers however. To counter your point that their breaks should have been cut in line with that of other countries, then we should keep in mind that some Northern European countries are going further in terms of workers rights, in the opposite direction, so all of us a sudden, your advice that we should follow the lead of some countries leads us to question which way we go.
I would also like to highlight that the CFMEU (Construction) enforces a 17 day shutdown over the Christmas break, so there are other's who do lengthy breaks.
I also struggle to understand your last point about bringing conditions in line within the country they live in, Australia has Union representation across most industries. If you wish to do business in Australia, then you surely understand this, I would hazard a guess that given this, then good conditions and decent pay is the typical situation. Why would anyone want to degrade that?
Winning a race to the bottom is a zero sum game.