And the people who have grown accustomed to taking cabs on a regular basis in Buenos Aires don't? I'm not trying to offend anyone but taking a cab is a luxury not a necessity (as it has already been pointed out). It's like "needing" a latte from Starbucks to start your day.
Personally, I don't know anyone from the middle class in the US that takes a taxi cab on a regular or daily basis. They either take public transportation, drive, or catch a lift from a friend. Why would it be any different here?