I used to work in this field several years ago. It’s gotten way better over time but there’s room for continuing improvement. Personally I think it’s a bit of

I used to work in this field several years ago. It’s gotten way better over time but there’s room for continuing improvement. Personally I think it’s a bit of everything: There’s almost no standardization in signaling protocols. Things like FaceTime and WhatsApp don’t interoperate. NAT hole punching remains a complex problem. It’s not easy to solve. Bandwidth is often not stable for long periods of time. Bandwidth drops, latency spikes, packets get lost or retransmitted. WiFi connections are sketchy. Wired connections are better but still packet switched. Cellular wireless systems are overloaded and suffer from multipath fading. Encoders are insanely complicated to build. Hardware acceleration isn’t easy to implement either. Configuring an encoders parameters for a connection environment is hard and remains a craft and not a science. The human eye seems to be much more sensitive to artifacts than the human ear. Cameras are hard to tune and expensive. Auto focus white balance etc effect call quality quite badly. Camera placement is still a challenge. Minor changes to lighting and colors can make huge shifts in quality. This is why video from dedicated conference rooms is way better than video calls from phones or laptops. The state of the art under controlled conditions is really unbelievably amazing.