Why don't you get off your high horse about internal flights in South America.
You say it is ok to take intercontinental flights but not internal ones, where land transport is feasible. So when you fly from the Netherlands to SA you could take a boat to the states and travel down to SA therefore avoiding flying. Now obviously you wouldn't do this because of time contraints.
It's the same for people taking flights in SA. Yeah sometimes you can take a bus, but if your vacation is short and you want to see as much as possible then sometimes a flight is best.
The planes will fly whatever, so isn't it better that they are full ?