When trying to keep the manufacturing in the united states every second of cycle time counts. And cycle times go through the roof in no lead/low lead brass especially in I.D. Work.
http://www.copper.org/resources/properties/db/SDResultServlet.jsp?Action=search&service=COPPERINTRA&ACtype=Wrought&Alloy=Brasses&term=Copper-Zinc-Lead%20Alloys%20(Leaded%20%20Brasses)&alloyStart=C30000&alloyEnd=C39999
see the link above. There is lead in brass.
There is no lead in brass? There is a reason why I am asking the question. In California laws are being passed as we speak to change what types of materials are used in the Plumbing industry.