I agree that much of this is opaque. But this is nothing to do with ExpertFlyer. These are the industry's rules, and EF is just reporting to you the information that is provided to it, in the same way that an expert travel agent would be provided with this information. EF doesn't pretend to be here to digest and explain the information; you have to spend time learning what the information means and how to make the most of it. If EF wasn't here, you wouldn't even have known what you didn't know about these fares; you'd simply have gone to the airline website and been presented with a take-it-or-leave-it price. The overwhelming majority of the flying public has always worked on that basis and continues to do so: you only need to see the number of complaints about how air fares appear to be randomly picked by airlines. They aren't - as you and I know - but almost nobody out there has much idea how it works, and I doubt that any regulator is going to require airlines to be any clearer about this than they are.

I don't agree that the dual inventory rule doesn't make sense. It's very simple to understand and apply: For the fare to be valid on a particular flight, there must be available inventory in one booking class and also available inventory in another booking class. The EF listing of these AA fares at least tells you (now that you know how to read them) that you need availability in the booking class corresponding to the first letter of the fare basis code (Q or N in this example), and you need availability in B class (as listed in the EF fare ladder). There are actually airlines which give you no clue as to which other booking class is required.