Your synopsis is incorrect, the story takes place in National City, but National City is in California, not Mexico. It's right outside San Diego. The fact that it's in the US makes a big difference.
Was this in an eNotes published synopsis? I am not familiar with the book. If there is a factual error in one of the eNotes documents, please let one of the administrators know. I have let Scott Locklear know about a couple of answers that have been in error. He takes this seriously, and really tries to have information on this site be credible.
I’m not sure what the conversation was about, but I am always glad to hear when someone makes an observation about how impacting the setting can be to a story or novel.