Some of us do. AAdvantage for one. As for your question about QF, the answer is that QF has contracted with AA to do so and has not with BA. A business decision. BA can afford to be arrogant -- they have your business without needing to pay for status bonus miles! And it works, as you do fly with them instead of using AA. Not a bad business strategy, optimized for BA's benefit and not for your benefit. It is interesting that QF and AA have a close working relationship (perhaps closer than BA and QF), for example QF bought a dozen 738s that AA had ordered and could no longer afford (this helped AA stay in compliance with its Boeing commitments). BA only sends worn-out falling apart planes to QF.