Basic rights for people who aren’t white dudes were mostly imposed by court order. That’s the reality. We have laws, it’s just that those laws were written at a time when personhood didn’t really apply to anyone who wasn’t a white man. And if no one who you consider a full person is capable of being pregnant, you’re not going to think to put in a right to abortion explicitly, even if it’s a basic requirement for equal citizenship for the female sex, because women (and trans people) aren’t really people…and so on.

Edit: I realize this is mostly due to the weird semi-religious fervor Americans have for our Constitution and government system.

TL; DR: We’re running Modern Democracy 1.0 with a Frankenstein covering of patches, while other countries just upgrade whenever they need you.