Should an 20 year old receive $5.15 an hour in a developed country such as America?
Why does the answer to that question even matter? Should they receive $100/hr? Would not $200/hr be even better?
Of course it matters because it determines their ability to live above the poverty line
What makes you so sure that If I was an employer I will hire just as many people as I did in the absence of a minimum wage? I don't have any obligation to hire anyone. I don't have to hire people if I don't like the price. As long as that is the case, the evidence is clear, minimum wages increase unemployment.
Wages have been going up for the past century yet our unemployment is at record lows...
So what? Who is to say that unemployment would not have been even lower in the absence of minimum wages? In fact that is the reality:
In 152 pages David Neumark and William Wasche discusses over 90 recent studies on the effect of minimum wages on employment, including 4 studies from Australia. Their conclusions:
"Minimum Wages and Employment: A Review of Evidence from the New Minimum Wage Research" by David Neumark, William Wascher
http://papers.nber.org/papers/w12663"We review the burgeoning literature on the employment effects of minimum wages - in the United States and other countries - that was spurred by the new minimum wage research beginning in the early 1990s. Our review indicates that there is a wide range of existing estimates and, accordingly, a lack of consensus about the overall effects on low-wage employment of an increase in the minimum wage. However, the oft-stated assertion that recent research fails to support the traditional view that the minimum wage reduces the employment of low-wage workers is clearly incorrect. A sizable majority of the studies surveyed in this monograph give a relatively consistent (although not always statistically significant) indication of negative employment effects of minimum wages. In addition, among the papers we view as providing the most credible evidence, almost all point to negative employment effects, both for the United States as well as for many other countries. Two other important conclusions emerge from our review. First, we see very few - if any - studies that provide convincing evidence of positive employment effects of minimum wages, especially from those studies that focus on the broader groups (rather than a narrow industry) for which the competitive model predicts disemployment effects. Second, the studies that focus on the least-skilled groups provide relatively overwhelming evidence of stronger disemployment effects for these groups."