A lot of other places outside the US. I don't personally agree with it, but for different reasons... it relegates a woman to nothing more than an object, or at best a head of cattle to be watched and used for the whims of the husband. The Bible has an awful lot of that, though, so I'm betting that's not why you disagree with it.
Anyway, Aineo... when he referenced the horses, he wasn't grasping at straws at all.. not by a long shot. He was supporting his claim that you were picking and choosing- according to your personal wants as an individual and human being- what you want to follow and have followed in the Bible. If the horse is right next to the woman in those verses (16/17), and they're phrased identically, clearly one is no more sinful than the other, yet the bit about horses is blithely ignored.
The US doesn't (uh, usually... I'm pretty sure Utah doesn't quite adhere to this) allow polygamy, but the US isn't a Christian nation (yes, most of America is Christian, but it wasn't predicated upon Christianity, nor were all of the founding fathers Christians by any means).