Originally Posted by irishguy28

The situation with Avios is rather unique amongst Frequent Flyer Programmes. I'm not aware of any other frequent flyer "currency" which is shared by so many airlines using so many different frequent flyer programmes.

Avios were an IAG "invention", formed shortly after BA and IB merged. The decision was made to retain separate frequent flyer programmes - BA still has its Executive Club and IB still has its Iberia Plus, and they are not just identical carbon copies of each other - and the decision was made to "share" a single frequent flyer currency, called Avios. Eventually, all the other IAG airlines (Level/vueling, Aer Lingus) - as well as Qatar Airways and Finnair - have eventually moved to adopting Avios as the "currency" of their frequent flyer programmes. But each of these airlines has kept its own frequent flyer programme, with its own (and different) set of earning and burning rules and partners.

But because of the shared "currency", these programmes include a means of transferring Avios from any of those FFP programmes using Avios to any of the other programmes using Avios (it's not always possible to transfer directly; for example, as you presumably have seen, to move Avios into or out of an Aer Lingus Aerclub account, it has to go via BA; you can't move Avios directly between QR and EI, it has to go through BA).

Air France and KLM went down a different path. Instead of retaining separate programmes and adopting a "shared" currency, they decided to share everything. Both Air France and KLM (as well as TAROM, Aircalin and Transavia) use a "shared" frequent flyer programme, called Flying Blue.

This "avoids" the need, arising from the airlines using Avios, to enable transfers of Avios from one account to another; all the airlines that use Flying Blue miles as their frequent flyer "currency" already use the same programme, so it's a more efficient and straightforward scheme; you don't need to have an account with each airline and there is consequently no need to allow "transfers" of Flying Blue miles between different programmes.

Coming from a BA/EI background, you might assume that moving frequent flyer miles between different programmes is the "norm" - it's not. And, in the case of Avios, it's only possible to move them between programmes that use Avios. You cannot move/convert frequent flyer miles from any other airline - not even the ones BA works closely with (such as AA) - into Avios. You can only move Avios into your BA account if those miles are coming from an account that uses Avios (so: Aer Lingus, Qatar Airways, Iberia, etc etc etc)