Why is lossless/hi-res audio quality poor in CarPlay?

I can't believe no one seems to discussing the quality of lossless or hi-res lossless when using CarPlay. I use a USB-C to connect to my car stereo and I can vouch the quality of lossless is much better plugged in than wireless. Furthermore, I am pretty sure I get much better audio quality by bypassing CarPlay and going with my car's default music player. Why? I believe the bandwidth when using CarPlay to play Hi-Res audio is compromised by having to transmit graphic data onto the screen from my iPhone simultaneously while transmitting audio data. I challenge others to prove me wrong.