Any Realtek TV tuner USB stick can be used. They are for sale everywhere in China.
There was a time before the Great Firewall too. These things can change. I bet China isn’t too happy about over the air video transmission that can cross borders either, and would prefer for citizens to use approved digital streaming methods.
My question is what does it accomplishes for China? Foreign armies and terrorists can still get plane positions, only average citizen can't. What's the point?
The state might want to move people or things secretly by air.
As I said, just disable ADS-B transmission when doing shady stuff.
That would imply they have something to hide.
Or, they want some parties to know what they’re doing, but not the citizenry.
Maybe this is overly paranoid but I don’t think we should underestimate the Chinese government.
China knows that direct control is hard to achieve at scale. They know they can simply state their intentions and let the chilling effects take over. Banning Flightradar24 is a statement of intention that every one of their citizens can see.