In general, the USA versions will have slightly better components and somewhat less variability than their Mexican counterparts. That being said, a lot of our perceptions around quality are based on our expectations and sometimes what we see.
If you took 5 USA basses and 5 Mexican basses that were more or less the same, had them professionally set up with new strings, and had people play them blindfolded through a clean amp (meaning they could only perceive how they played and sounded), I think that it would be difficult for people to always think that the USA versions were better. This might be an interesting experiment to try.
If you took 5 USA basses and 5 Mexican basses that were more or less the same, had them professionally set up with new strings, and had people play them blindfolded through a clean amp (meaning they could only perceive how they played and sounded), I think that it would be difficult for people to always think that the USA versions were better. This might be an interesting experiment to try.