Well, not everyone wants to take the train to Zona Norte when they just need some air out on a walk or after work. And not everyone can live in Palermo or Puerto Madero, even though those two areas have some excellent parks. It's true that a lot of neighborhoods, especially moving away from the river, are lacking in greenery. But I think BA still feels greener than it is because so many of the streets are tree-lined. That's something you don't get in every city of this size.