Gonski's moral needs to be rational

Comments on Julian Savulescu and William Isdale "An ethical education: why Gonski is a moral issue", 11/04/2013, https://theconversation.com/an-ethical-education-why-gonski-is-a-moral-issue-12849
While I totally agree with the importance of education and the importance of increasing equity in education, I was less than fully satisfied by the article due to its lack of comparative analysis of the cost and benefit of the investment in education between Australia and other countries which the author mentioned in the article.

More specifically, the article unquestionably endorsement of the Gonski recommendation of amount of increased funding by governments is questionable without those comparatives.

The question is: some other countries achieved better results, are they all the results of greater investment per student than Australia's or not? Such information would be helpful to proper judgement or analysis/evaluation of the increased amount recommended by Gonski.

Another question is the relative decline in performance of Australia's education compared with some others. What are the reasons? It is not the right approach if it is based on the model that there is a problem then there must be more investment.