Who gets paid for coordination?

Generally speaking, the engineer is responsible for designing a system that can fit in the space provided.  Coordination is the responsibility of the General Contractor (GC).  You don't believe me? Check your contract. There will be about a 15% allotment for coordination given to the GC. Who is responsible for submitting coordination drawings to be approved? The GC. It is the engineer who is responsible to review and approve or reject them. These tables seem to have been flipped with the introduction of BIM.  On every single BIM job I have worked on, the GC has complained about not being provided a "fully" coordinated model.   Upon investigating further, the clashes were often minor and insignificant. Things I would expect to be resolved through the coordination drawing review process.  Further more, these models are much more coordinated then any of the 2D cad projects we have produced in the last 20+ years.  Why were there not the same complaints then? I believe this is an excuse for the GC to get more time and to reduce their cost of coordination.  Can or should that 15% fee be moved over to the engineer?  We are doing the work anyway.  Then would we be agreeable to taking on the increase in liability that comes with coordination? Some would say that we already are when we approve the coordination drawings. How should this contractual arrangement be revised?  There seems to be an expectation by the owner and GC that if Revit is used on a project by the design team, the model must be perfectly coordinated by the design team?