Many large governments do this. The US does too probably:
"It has been reported that HBGary Federal was contracted by the U.S. government to develop astroturfing software which could create an "army" of multiple fake social media profiles.[36][37]"
But this would be such a sinister thing - testing bioweapons on citizens - that catching an astroturfer would be a huge scandal. It wouldn't be worth the risk. This isn't fracking.
Downvoters: If you really think I'm wrong, then this is the story of the century. Stop whatever you're doing and start a doxxing effort against these astroturfers. You believe the government is literally trying to shape opinion in favor of killing its own citizenry. What could be more important than this story? Get to it. This is Pulitzer stuff.
"It has been reported that HBGary Federal was contracted by the U.S. government to develop astroturfing software which could create an "army" of multiple fake social media profiles.[36][37]"
https://en.wikipedia.org/wiki/HBGary#Astroturfing