Are Realtors being used when buying a home from a builder?

[Ryan Acker]

A co-worker of mine is in the beginning stages of buying/building a new house in a new development that is just now under construction and will be selling the house she lives in now.  I was curious so I asked her how she found the realtor to list her current home and she said the builder.  The builder recommended a realtor that will list her current house for 4% vs the going rate in central Ohio of 6%.  So 3% going to the buyers agent and 1% going to the listing agent.  I found this interesting and wondered if this is a common practice between builder and realtors.