An old and worthwhile Working for Change essay ponders the difference between labor unions in America and Europe, an important topic in its own right:

In the United States, where CEOs continue to inflate their obscene paychecks while laying off workers during a recession, unions are notably weaker than their European counterparts. It's hard to sort out cause from effect. One of the reasons they're stronger in Europe is that they're less timid (and therefore more effective in advocating members' self-interests), and one of the reasons they're less timid is that they're stronger.

But how did this all come about? It might help to take a gander at the historical record. Way, way back in the late 19th century, remember, the labor movement in the United States was arguably far stronger, less timid, and much more progressive than its counterparts in Europe. The Knights of Labor, the premier worker movement of the time, took an active role in organizing minorities, women, and unskilled laborers, fought for broad-based social change—including civil rights, gender equality, but also economic upheaval—and even ran explicitly pro-labor candidates for office. But in the end, the invisible hand of the marketplace grabbed a very visible arsenal and employers cracked down violently on the Knights—often with the assistance of state and federal troops. (The railway strikes in the 1890s and Homestead steel strikes being the classic cases.) European governments, by contrast, reined in at least some of the organized violence against labor, which made, I think, all the difference in the world.

As histories of labor all note, the successor to the Knights, the relatively-conservative AFL, learned its lesson—don't rock the boat too hard—and instead focused its efforts on winning somewhat narrower victories: working with specific companies to negotiate workplace protections and higher wages rather than sweeping social change. (It helped that the AFL signed on to the battle against communism, too.) All through the 20th century, this pattern repeated itself, especially after more radical movements like IWW were repressed, until it became essentially routine by the 1950s. During the health-care battles in the postwar era, for instance, union leaders such as Samuel Gompers and George Meany preferred to negotiate benefits through collective bargaining agreements rather than push Congress to pass universal health care. In Europe, organized labor took the political route and had both the means and breathing space to do so. That's a picture drawn in crayon, to be sure, but not entirely inaccurate.

This dynamic, in turn, brings us to the chicken-and-egg phenomenon discussed above. American unions today just aren't muscular enough to link arms and heave up a robust welfare state (and they certainly won't get any help from the Democrats), so instead they concentrate primarily on individual bargaining victories. "Business unionism," some call it. But precisely because a robust welfare state doesn't exist in this country, corporations face even greater pressure to resist these narrowly-tailored union demands—like better health care benefits—since doing so would put them at a competitive disadvantage, both at home and abroad. Breaking this vicious cycle obviously requires a good deal of work, but that seems like the main difference between the two continents.