Empty PCB? You can’t see the other side of the logic board in this video. All reputable computer manufacturers use circus design on PCBs.
The cost of the dock is high because the tech is new. I don’t believe I need to explain the cost curve of advancing technology to you.
Technically, yes, data must transmit to negotiate, but it doesn’t require high throughput. So you’ll get USB 2.0 transfer speeds (480 Mb/s) with most “charging only” USB-C cables. That’s only really useful for a keyboard or mouse these days.