A seems to support the fact that Mexico did exist in Red Dead Redemption 2 with Nuevo Paraíso being the helm of it.
https://reddead.fandom.com/wiki/Nuevo_Paraíso
Seriously, you fall in love very easily with those who likes and know how to to cook decent meals. It's like the good food creeps into your heart and arrests it.
It's an added advantage for the gaming system to run both digital copies and disc copies. Hell, it even saves you some cost on some games that are more expensive on digital content.
I do agree with you on that being an exploitable glitch that helps to make that possible. There is a detailed article on how that's done here even about the YouTuber ZacCoxTV who discovered the Mexico glitch.
https://screenrant.com/red-dead-redemption-rdr2-mexico-map-location-glitch/
Seriously, that's why I hardly ever look into their eyes whenever they mess up because there is no way they wouldn't melt my heart with these looks in their eyes.