I did a bit more digging into this one yesterday and there’s something fairly unique about VVI right now. I was thinking maybe this is a fare sale that might apply to other AA fares that include a tag-on of a G3 flight. But I can find no indication that is the case.
However, base fares in the reverse direction are roughly the same. United also has similar base fares, again both originating in US as well as from the VVI. By the way, both carriers also have fares filed as a OW (either departing the US for departing the VVI). For AA, the one way fair can be in the $600 range, so definitely something to consider for flexibility, and then using miles or an ex-south america fare to get back. I mentioned United, although roughly the same base fares as American, they price out higher. If you look at a fare breakdown in ITA matrix you can see why.