Depends on the update.
If it’s a full system overwrite, they would put a delay to go via wifi first then 4G if not done by x date
Smaller updates, 4g immediately.
Tesla would have a global contract with the likes of AT&T to deliver data to every modem installed, and they would have allocation limits to meet that.
The China article was true that they launched the service, but bullshit they are the fastest.
Plenty of other countries are running 10GB and faster services you can get to your home.
Sweden for example