Far be it from me to defend Peruvians, but:

Why wouldn't they "sell exactly the SAME recording in diverse parts of the world"? That is a bizarre criticism - isn't that what all (financially) successful musical acts do?

If they are playing "western pop standards", it is no doubt because that's what they make the most money playing. In other words, it's what the public rewards them for playing. In other words, it's what the public prefers to hear.