When I was a teenager (late '80’s, early '90s), living in a suburb, I got a bit under minimum wage, or $2-3 an hour, IIRC.
Now I’m a grown woman, with children of my own, I studied child development and psychology in college, I have first aid certification, a house full of toys, I provide healthy organic meals out of pocket (well, out of my fridge, more precisely!), AND I live in the City of Chicago, where everything costs more. I’m also more likely to sit for 6 hours or more, so I’m a bit of a preschool teacher as well, keeping them busy with arts and crafts and going to the park and learning stuff, not just making pizza and watching The Little Mermaid before bed, like I used to do as a teenaged sitter. $10/hour is on the very low end for adult sitters here*, and it’s what I charge, mostly because my only two regular clients were friends of mine first, and I see each of their kids at least once a week, so it’s sort of steady work. I also have to pay taxes and health insurance out of that (since I make more than $600 a year), so it’s not nearly as much as it sounds. ETA: I don’t pay for liability insurance, which I know I should.
In December, I’ll have my first set of siblings, and I’m trying to figure out what to do about it. Obviously, the newborn will be a lot more work, but charging the mother double what I do now will push it into the not-worth-working range, and I don’t want to lose her. I suspect I’ll go half rate for the sibling if I have both of them at once, and the full $10 for either one alone.
I think the difference is one of public perception and self-valuation. I remember a lot of talk when I was studying child development (with the idea of working day care, which I later discarded) back in the '90s about “Why are people paying more for the people making their burgers and fries than those raising their children? Where are our values?” I do think that people are willing to demand a higher quality care and reward it appropriately these days.
*Here’s a cached Sun-Times article on recent averages in Chicago, for those that think I’m making this up.