Fees received by real estate agents and the like always baffled me.

In a somewhat related story:

Earlier this week I was approached by a builder, I did not know, to design an addition for one of his clients. After discussing the project for several minutes I directed him to give my contact information to the client and have them contact me, I work directly for the homeowner. He asked me how he gets paid, how he makes 20% off of my fee; he wanted to know if I pay him after I get paid from the homeowner or how that works. I told him I do not work that way. My relationship is with my client and the builder does not make money off me; I provide the service and my client pays me for those services. I have not heard anything from the builder or the client since then, and I do not expect to.

Sounds like a very greedy person--the builder is going to make money from doing work for the client. Why should he/she get a cut of your fee?