First, let's note the differences. Doctors and lawyers in America are not as low on the social scale. Because of their high level of education and the amount of money they make, they enjoy a high degree of social status. In Germany, according to Fred, doctors make comparable money, but do not have as high of an earning potential as say American brain surgeons because of Germany's socialized healthcare system. Lawyers are not as well respected in Germany because the legal system is different. In turn, they do not make as much money.
Now let's examine why bankers, industry bosses, and university professors are at the top of the ladder. Banking and manufacturing are the biggest industries in Germany, and together they account for a large portion of the country's wealth. Therefore, it follows that the heads of these industries would enjoy elite social status. Also, in Germany there is a high emphasis placed on education, at every level and particularly at the University level. Getting into university is highly competitive. The central government pays for German students to get a higher education. Therefore, some of the best intellectuals in the country hold prestigious positions in German universities, usually because they had to work so hard to get there.
A final pattern that can be examined in this German social stratification is the status enjoyed by owners of small businesses and craftsmen. Although great emphasis is placed on education, trades are very well-respected. Highly gifted craftsmen and successful businessmen can achieve the status of doctors and lawyers, whereas in the US this is generally not the case.
Generally, the success of the individual in German society depends greatly upon education and opportunity. However, it depends less upon the social class that a person comes from. For example, a German doesn't have to come from the Kennedy family of Massachusetts to become the Prime Minister. I would venture to guess that there is more upward mobility in Germany than in the U.S. But once a person fits into a particular social class, the lines are more rigidly drawn. For instance, it is common for people to stick to the same career their whole lives. Stability is a sign of achievement, whereas in America we hail an NBA all-star like Michael Jordan when he decides to take up baseball or golf. I think we are more open minded about career and educational paths, whereas in Germany and other European countries the expectations of the young are more rigid and formalized.