I get your point but there are a lot of bands from other South American countries that sing in Spanish and have big hits, Argentina and Columbia have had very successful bands. I think part of it is a self fulfilling prophecy, no rock band from here has ever been successful from Peru so they don't try but there's also very little support here. I have seen some very good bands here though.
This is a very interesting band from Peru, UCHPA, they are part folklore and modern and sing in a language called Quechua from the mountains, I've seen them, they're very good live, song about beer
Here's some recent straight ahead rock bands from Peru who sing in English, the problem is they're not really very original.
Soda Stereo (Gustavo Cerati) and Juanes are two off the top of my head who sold a lot of records out here. I think both Columbia and Argentina are much more rock oriented countries though and support the music, out here? Naa. But spanish music is big business in the Spanish speaking countries.
I bought this album when it was current: Siempre es Hoy- Gustavo Cerati He came from a band called Soda Stereo from Argentina who were very well known here, still are,
Juanes from Colombia- I also bought this when it was new.