Going back to the original topic of the thread, I was reading an article that was linked in the Menzoa thread that was mainly based on that location - but it did give an insight in regards to lack of accents (and presumably the same reasons apply to other locations, not just Mendoza).
Argentinian players were disappointed by the lack of a proper accent from NPCs, which the developers attribute to lack of time and budgetary constraints. The Covid-19 pandemic also made casting and recording new voice actors far more difficult than usual. In the end, the team chose to focus on voice talent that would fit the Chongqing level rather than Argentinian voice actors.
“We decided that reusing our Colombian and Mexican accents was still better than having British gauchos,” Ansdal explains.