(I'm not a SME, but I looked a bit into this while buying a bluetooth headphone)
Audio works with some bluetooth specific codecs like SBC, Qualcomm aptX (adaptive/HD), LDAC, ... or Opus and AAC
These codecs need to be supported by both sender and receiver.
And for example many bluetooth speakers only support SBC as they don't want to pay the fees for aptX and LDAC (which are both codecs that sound and work very well, LDAC even supports up to 96 kHz sample rates with 32 bit depth).
So I suppose (i don't know for sure) problems could be a) audio is more of a special case with all its codecs b) SBC is widespread, but does not sound good c) codec support on operating systems and bluetooth chips varies widely.
If that's the case, why does audio work so badly? (I'm guessing there's a list of exceptions that BT supports natively, none of which work.)