I've been to the Bacardi distillery in Puerto Rico. You're definitely right this is rum production on a massive, industrial scale. For comparison I've also been to the Barrilito one, which is like comparing the earth to Jupiter in terms of production mass. That's a great rum.
Barrilito is actually made from Bacardi bulk rum, and they do add flavorings, but they don't hide the fact. They're basing it on a Spanish tradition of adding fruits, etc to barrels while aging (or something along those lines), very similar to the now-outed Matusalem formula. Perhaps our resident Borinqueño knows some more info.
I really like Barrilito, and again, since they don't hide the truth I'm fine with them, but it goes to show how mega-industrial, no taste rum can be altered to be quite tasty, a practice that's unfortunately quite common and rarely if ever disclosed.