What I primarily write about is cultural myths and the actual facts and truths that dispel them, and I encounter this constantly. "Everyone knows" is how it usually comes across but it's essentially the same as "common sense tells us." And as you noted, people often cling to this stuff because it's easier than doing the work to become better human beings and co-creating a better society. They don't want to have to face things that are challenging or uncomfortable - all the while talking about how tough and strong they are.