I'm quite sure that AA does not "want" you to play fuel dumping games. Taxes on international flights are fixed fees and are not charged as a percentage of the base fare, so there are no tax advantages here. As various threads have explained, the carrier imposed fee sets a base price for negotiated discounts and enables airlines to adjust prices without having to go to the expense of filing new fares. Pricing for revenue tickets is not impacted by the fee as if there were no fee, airlines would just incorporate that amount back into the base fare. Ticket prices are set by market factors and it's false logic to assume that if there were no carrier imposed fee, your ticket price would simply go down by a commensurate amount.
I often wonder if the surcharges are a way around taxes, for the airline and not the consumer. I'm sure there is a tax lawyer on here who might have some insight. Corporate tax structures are complex and maybe I am right. Or maybe I'm out in left field.