Because they must license the electromagnetic spectrum from those countries. It would also be trivial for those authoritarian governments to track people using those dishes and punish them.
1) What is the penalty if they don't license spectrum? Will Russia and China shoot down Starlink satellites? Or impose sanctions and disrupt their supply chain?
2) We all know that Ukrainian sea drones are using Starlink. They wouldn't do it if it was that easy to detect.
