Well the cultures of the states differ significantly. It makes sense to me that regional variation would reflect in laws.

I grew up in southern MO. Arkansas was only about a 40 minute drive away, but I can always tell when I'm there compared to at home. The people dress and look a bit different, the houses look different, it's just a different culture. California and New York are like alien worlds to me. The idea that such different people should live under the same framework seems like a good way to amplify regional tensions.