Why does it seem like....?

The race in the United States, while it is open to many of the parties you mention and many more others, cannot handle across-the-spectrum politics they way many other parliaments worldwide have. So, so-called "third party" ideas are usually absorbed after the fact by one of the two so-called majority parties. Fair? You tell me?

The young whippersnappers have no concept of what a nuclear bomb is really, so how would they know about the Socialist Workers, Greens, American Independents, etc.