Why do some jobs earn more money than others?

Molly and Carl have just found out that some people earn a lot more money than they do, and this just makes no cents (pun intended). So how do we decide what different types of jobs should be paid? What about if those jobs are dangerous? If they take many years of training and study? Or if they will make the world a better place? Brains Trust – Linden Park Primary School, Adelaide – Genevieve, Grace, Alexa, Poppy, Chelsea, Sophie