This isn’t completely true, children actually can be married at that age including to adults in some states. There’s also no such thing as statutory rape between spouses in this circumstance. The kid’s spouse also usually become their guardian, so they cannot get divorced without the adult spouse’s permission in many places.
That’s alright, I kinda used your comment to spread awareness about child marriage in the US. I want people to know so they can vote to ban it. Overwhelmingly most voters in the US do want to ban child marriage but they don’t even realize it exists.