The question in the headline is fundamental when trying to understand attitudes towards organized labor, as well as the relatively low union presence in the U.S. The "if I can't have it, nobody can" attitude that anti-labor advocates try to promote among non-members packs far less punch if people understand that many of the conditions they take for granted - trivial things like sick days, minimum wages, and yes, weekends - are in no small part thanks to past and current efforts of the U.S. labor movement. Awareness of these efforts, and of the positive union effect on everyone's wages and benefits, is also, no doubt, partially dependent on one's experience with unions (e.g., coming from a "union family").
So, it might be instructive to take a quick look at attitudes towards labor's effects in the U.S. compared with those in other nations, and whether this appears to be related to the degree of unionization. Basically - do Americans think unions help all workers, and how do our attitudes stack up against other nations?