Should child-care workers be paid more than plumbers because it's "more responsibility"?

Something is only worth what people are willing to pay for it. Most people will pay more for a plumber than for a childcare worker. Partly because plumbing is something you need a complex training for, whereas childcare is a simpler thing. Partly because most people who want childcare need it done every day, and most people couldn't afford to pay a childcare worker at the same rate as a plumber.