My hypothesis about these European leisure routes has been that AA probably sells a bunch of tickets through travel agencies and other bulk channels (e.g. targeting cruisers), and thus the off-the-shelf fares are more about maximizing revenue from the odd one-offs that actually need to get there for some important reason. AA does have profit-sharing with BA, so it gets a bit if people go that way. And if it can grab a big chunk from the cost-no-object folks who need to go direct (e.g. for business), then they probably figure, why not?