I've actually seen more extreme differences in traveling across the UK. I've had UK money refused (Scottish tender in England), in parts of the UK you have different native languages like Wales and the Scottish islands, different laws, different education systems. While for an American (my wife is Texan and grew up on a working ranch) there's a lot of difference, I don't see as much. The geography is a lot more different, the culture less so outside of very narrow areas. The UK actually feels like separate countries which is because it kind of is.
I spend most of my time in the US and Texas, Florida, and Idaho and never had much of an issue. Outside of the climate and licence plates there's very little difference between states. The US banking system is 20 years behind the UK, that does irritate me somewhat. I don't know how to write a cheque and magnetic strips are never used in the UK for example. I also have no idea how to use a fax machine.