Mexico has gun laws which are significantly more restrictive than the USA. There is only one legal gun store in the country, they must all be permitted, calibers are limited, and only permitted within the place of residence. "Monopoly on violence" is an illusion that's propped up mostly by the culture of the people who live in a country.
Sweden's gun homicide rate has increased by 400% since 2010 due to nothing other than demographic change.
In the 1990s, I traveled into Tijuana from San Diego County a few times. We usually walked, because of reasons.
For people traveling north into the USA, the border checkpoint included long queues of vehicles and people alike, customs inspections, routine searches of everything, passport checks, and questions by actual Border Patrol officers.
Walking south into Mexico, there was a broad, unsupervised walkway and a one-way turnstile. Large signs read:
And that was it! We were in Mexico!