:Author:   John Powers
:Date:     Tue, 11 Sep 2007 12:13:04 PDT

It isn't necessarily a cost savings when people bring their own bottles to be filled; the reason is there are transaction costs.  When products are packaged in advance great care can be taken to measure the right amounts and it is easy to inventory simply by counting units.  

When bulk materials are measured out per customer there is the time it takes for the person to fill it.  Also it opens up all sorts of opportunities for mistakes: more opportunity  to spill, different kinds of containers, forgetting to mark down a unit sold, etc.