Work wasn't considered an "adult" thing in the past, though. It was something everyone did as soon as they could walk and had basic hand-eye coordination. And it's only extremely recently that voting has been connected with adulthood, even in the history of voting being something people could do. It used to be connected with being a white male property-owning citizen head of the household, and of course you'd be a certain age to be the head of a household. Having adulthood grant rights and privileges under the law, and having childhood be work-free is, relatively speaking, a brand spanking new thing. However, people still wouldn't think 13-year olds could run their own households by any stretch of the imagination.