Ok being blonde dont understand how Zwift controls my watt bike but not treadmill ???
Combination of liability issues and protocols used by treadmill manufacturers.
On a bike there is no risk of you getting thrown off if all of a sudden Zwift tells the trainer to hold higher watts or go up a 12% grade. But if Zwift controlled the speed and incline of your treadmill it is possible that if you weren’t paying attention and the pace went up during a workout and you weren’t ready you could injure yourself (same thing with auto incline).
Maybe one day they will work it out but currently they most likely don’t want to open themselves up to a potential lawsuit if someone hurts themselves with a controllable treadmill on Zwift.
Never thought of it like that. Thank you, new to all this