I am from Mexico and there are some facts and details in your story that I haven't realised about them, it's very common and you don't stop to think about it, like the anarchic road system haha. Nice to know that most of your trip was enjoyable and you learned many new things.
About the Miles/Kilometers topic: I don't understand why the Chinese refuse to use standard symbols to write, nor do I understand why USA people don't change to a standard system of measures.