For most countries, the departure taxes are charged to the airline, and they pass it to you on your ticket. EZE and UIO I had to pay taxes out of pocket, everywhere else DL paid it and then took it from my next paycheck. If you're on a ZED ticket, it is added on to the price. You'll see for instance "Base Fare:25.00USD Taxes:79.87USD Total:104.87USD." Those departure taxes and USA arrival taxes are included in that taxes block. Now, most countries have more than one tax/fee. So that 54USD most likely includes the 15USD NAS departure tax.