Three notable points concerning the $15 Australian McD wage:
1. Many McD's employees will still earn less than $15. Teenagers, a very large portion of both the Australian and American McD workforce, will still earn around AUS$8, around the same amount they earn in the US.
2. Australian dollars are worth less the US dollars. The equivalent american pay would be around $13 to 13.50 per hour. Definitely better, but not nearly as significant.
3. The article acknowledges that Australians pay more for McD products. Americans might not be willing to incur the additional cost, Exhibit A - Walmart. Similarly, the article mentions how McD profitability is also already lower in the US than in Europe and Australia.
The quest to improve the wages and conditions for entry level employees is noble and worthwhile. However, facts and context are necessary for honest debate.