Tom, aren't at least stall warning devices a crude angle of attack indicator? If they were based simply on speed, they wouldn't go off in an accelerated stall.
Also, please note the image below from a Cessna.
Confirming my supposition, I ran into this comment from you:
(found this after I made my post)
Correct, they work on AoA and actual airflow which makes them even more accurate indicators of stall than the ASI. The other day when I did my BFR I was doing a short field landing and my CFI indicated "we're below the white arc", "you hear a stall horn going off (I knew it worked since we had already done stalls and slow flight)?" "Nope" "We still flying?" "Yep" "then we're fine."