I think when people, particularly in America, think "protest", they think of people walking around with placards and other such relatively low effort involvement. That article is talking about incidents where you have 3.5% of people (that would be 12 million people in the US) engaging in things like organized and real boycotts (as opposed to 'Yeah I'm boycotting [this place I've never even heard of, let alone shopped at]), strikes, and so on.
You could have tens of millions of students and otherwise unemployed individuals walking around with placards, and nobody's going to care. But get 50,000 truckers (let alone 12 million people) to go on strike over something, and the whole country will grind to a halt.
You could have tens of millions of students and otherwise unemployed individuals walking around with placards, and nobody's going to care. But get 50,000 truckers (let alone 12 million people) to go on strike over something, and the whole country will grind to a halt.