BrianZ, your definition of "productive" assumes perfect knowledge by others. Real-estate agents are useless to me because I am smart enough to do the work myself, and have the time to do so, but not everyone is and does, respectively. So to them, there's productivity in letting someone else handle that aspect of their lives. This holds true for the other jobs you listed, too.
Agreed. The problem is that we are our own worst enemy sometimes. With the amount of greed and corruption that takes place, society has had to put so many laws, policies and procedures in place that we need "non-productive" people to make sense of it all.