There are vendor A2DP codecs that support duplex audio (faststream; aptx-ll optionally) but very few devices implement them. Software support is also fairly bad, although on Linux Pipewire does support them.
Also iirc CSR has a vendor codec (Auristream) in SCO transport that supposedly provides higher quality. Not sure how much better it is, or what software supports it.
So certainly better duplex quality is achievable. But there may be some licensing, hardware, or software support constraints that have prevented them from becoming more common.
Also iirc CSR has a vendor codec (Auristream) in SCO transport that supposedly provides higher quality. Not sure how much better it is, or what software supports it.
So certainly better duplex quality is achievable. But there may be some licensing, hardware, or software support constraints that have prevented them from becoming more common.