They're influential elsewhere, too, and not just in authoritarian countries or from the authoritarians themselves. China is fond of using a mix of bots and human-guided social attacks on Taiwan's President, but it also faces "several" large anti-government Twitter bot networks. Meanwhile, bots and other propaganda systems have attacked political figures and rallied protests in Brazil ever since the 2014 presidential election and the ensuing scandals. In Poland, a handful of right-wing accounts represent 20 percent of all political discussion in the country. All told, the researchers found 29 countries using social networks to skew opinions at home and abroad.
And the US certainly isn't immune. Twitter bots achieved "highly influential network positions" during the 2016 presidential election, particularly among the pro-Trump camp (where a key botnet was three times larger than that for Clinton).
This isn't to say that bots are always bad, or that democracies are defenseless against influence campaigns. Canada's political parties use bots, for instance, but they're also used to improve public knowledge. And Germany is a "leader" in fighting online disinformation campaigns between regulation and an abundance of watchdog groups. The tricky part is keeping a lid on digital propaganda without pushing the social networks too far. Companies like Twitter will tackle bots, but they tend to push back when asked to decide what's true or false. It may be some time before we see numerous democracies finding a way to curb propaganda mechanisms without undermining their own free speech values.