Early on in my time in Japan, I spent a few hours a day (for about two years) in the conversation lounge area of the school I worked at (Nova's "Voice" room). In this area, the teachers had free conversation with students. For those who don't know about the English language school situation in Japan, there are roughly two types of lessons. One is following a textbook to study specific phrases or grammatical structures and the other is just chatting with students so they have a chance to practice their English. The worst part of spending time in the conversation lounge was that the students were often completely passive so the teachers were constantly under the gun to come up with topics. Generally speaking, this resulted in the teacher choosing a topic which he or she had concrete opinions about because, when queried, students tended to react with indifference or be mute.
I can't recall any specific conversations I had at that time since it was so long ago but I do remember feeling at times as if I had to "educate" the Japanese with my perspective and contrary opinions on important topics. I remember that they rarely argued back or offered their own perspectives or opinions except for maybe on statement of support or opposition and this made me feel as if I'd somehow "won" any discussion in which they disagreed initially.
My behavior back then pretty much sums up why the Japanese people feel Americans are strident, pushy, and unable to control their feelings. To them, we are little better than children in this regard because we feel it necessary to disgorge our opinions at the slightest provocation. What's more, we often do so at great length and with increasing volume if our passions are aroused. In most cases, if a student expresses an opposing opinion, a newbie teacher will verbally stomp all over the student until he or she mumbles something in surrender.
The truth is that those of us who engage in verbal tangles with Japanese people over weighty issues aren't winning with our superior points. In many cases, the Japanese people are simply withdrawing from the discussion because they value getting along more than asserting their opinions and they've grown up in a culture which values restraint over expression, particularly in a situation where someone might be perceived as an authority figure (such as a teacher).
One notion you learn after some time in Japan which appears to be absent in American culture is the idea of restraint when expressing opinions and ideas. In the U.S., arguing is almost a sport and we all want to win. Unless we're dealing with someone who is in a position of power over us (like a boss at work), we rarely tend to back down or keep our notions to ourselves, even when there is the potential for a relationship to be damaged or lost as a result of the strident expression of one's views. The right and habit of being vocal is an integral part of American culture which is likely rooted in the rebellious beginnings of the country and certainly incorporated into the constitution.
In a country like Japan where restraint and a focus on group harmony are the cultural norm, this can cause some pretty big clashes. In fact, one of the greatest problems for cross-cultural relationships (both romantic and friendship-based) can be that one party is showering the other with input while the other is staying mum. On more than one occasion, I've had students tell me, "Japanese people don't like giving opinions," as they struggle to deal with a question I've asked. It's not that they lack the English but rather that they don't have a practice of thinking deeply about such topics or of expressing ideas about them. That's not to say all Japanese people are like this but most are to varying degrees.
I've come a long way since my smug days of offering my opinions in the Nova Voice room. That doesn't mean I don't offer them when they are solicited but rather that I offer them more briefly and with a far more open-minded attitude rather than thinking I'm right and have to prove it.