Not a surprise that this wasn't smooth! How is one to know if we need to purchase exit tax prior to flight or not? United is a good data point, but what about Copa flights? Avianca?
Living here, going to a Hotel to get exit tax, does not really help. I send the messenger to the bank a day or two before, because I do not do lines very well. But how do I know if I need it? Oh well, like most things, in a few months, or longer, things will work themselves out, and the worst that could happen is I will pay twice for a flight.
Look how far we've come since buying a group of exit stamps from shady characters outside the airport 15 or 20 years ago. For a time $64 worth!