Another (more convoluted) example is what AA has been doing with fares/ticketing in Venezuela (VE), where the local currency is highly devalued, foreign currency exchange is state-controlled, and where there is a rather transparent black market for foreign currencies. About 3-4 years ago, AA started by implementing new rules for all fares ex-VE (including xONEx) that required local currency/local billing address CCs to purchase tickets. Plus, tickets could only be payed for in person at a local AA office. This initial rule was put in place to prevent people from making "technical" stop-overs in VE to take advantage of the very convenient (black market) exchange rate. That lasted about 1-2 years, until AA dropped it altogether due to, in part, conflicts with VE government over the massive debt owed to AA (ongoing). At this time, AA does not accept local currency/local billing address CCs for ex-VE tickets anymore — they only accept foreign currency CCs, that is, the exact opposite of the initial rule. In fact, you can only purchase ex-VE tickets by calling AA reservations in US or doing it online on the US site. Local AA offices in VE don't make reservations anymore, the only payments they process in the local currency are mileage ticket taxes/fees for ex-VE reservations strictly made online (and this could very well change too leaving the AA local agents with nothing to do!). Albeit at times vague, AA did include these "evolving" changes in fare rules. There is a lot more to say about the VE example, and it is certainly different and more extreme than the other cases discussed in this thread. My point is that AA aggressively pursued and implemented those fare rule changes even if some were/are illegal. Having experienced the resulting complexity (and at times impossibility) of ticketing ex-VE AA flights, I would agree that perhaps is best, whenever possible, "to find work-arounds rather than pull the lion's whiskers”...