I'm really surprised by this, there is an official cab office right outside ezeiza, which gives it some legitimacy. How did you pick a cab? (i want to know which ones are actually unsafe)
I am really careful at the points where you will find a lot of tourists like Ezeiza and the central bus station. We've got screwed by a "tapper" once, paid much more for the ride than was actually supposed because he rigged the meter. This happened just outside the bus station where they're waiting for victims from out of town that don't know the tariffs, distances etcetera.
Hailing on the street never went wrong.