I don't really understand how it is selfish to take a child with you on an aircraft. Personally, I don't think the notion of excluding 12.8% of the total population (according to the Australia Bureau of Statistics 2011 census data) is particularly fair at all. Now, there are almost 5.7 million families in Australia, with an average of 1.9 children per family and out of the 5.5 million households in Australia, 71.5% are family households, who at one point or an other, may have travelled in the past with young children, or may want to in the travel with young children in future.
And you think those young children, and by result, the rest of their family, shouldn't be able to travel by a method of public transport? I really would implore you to explain, for the benefit of the majority (who's households make up almost three quarters of total households in all of the Commonwealth), how the notion outlined in your previous comments is not completely devoid of any ignorance or selfishness, and how the desire for the majority to travel with their young children is so clearly selfish.