None of that are physical limitations, it’s purely implementational. Legacy ethernet was half-duplex as well, before switching and dedicated pairs for tx/rx became the norm. Handling of the shared medium is done with CSMA-CA and not -CD, which was used for ethernet, so at least we learned something.

Copper is also susceptible to interference, both RFI and EMI. Sure you can mitigate the effect by shielding and twisting the wire pairs with different amounts of twists pr length. But in the end, copper is also susceptible to interference.

I’m not an RF engineer, and I don’t have an idea of what can be done to mitigate noise in wifi even further. But claiming that it’s an inherent physical limitation, that can’t be mitigated, that’s just defeatism. It’s about the implementation, not physical constraints.