Tuc,
I can confirm everything you said in your last post - and improbably, it's even worse now.
On a recent project I was involved with, there was NO detailed independent 'should cost' estimate. The PM started with a figure that was dreamed up between the two star and the (sole) supplier. No full cost model was prepared (despite being offered by contractors) because that was said to be 'the contractor's job'. The contractor then refused to provide a full cost breakdown, and was backed up by the PM and the TL because , we were told, 'we can trust them'.
CAAS were also cut back, and are still being rebuilt by KPMG. Their ability to cary out any decent cost investigation was hindered by a lack of requirements and any decent technical description of the modification being proposed.
And it gets better - the 'modern' way is apparently to get the contractor to write their own Systems Requirements Document (SRD). Of course, any document coming out of this process is absolutely, completely, fully, risk free 'up front' - which results in a document that doesn't even line up with the original URD. Our RM (a really decent and hard working guy) was in a constant state of despair. You are absolutely right - lack of proper requirements capture and articulation is the biggest challenge DE&S faces.
Best regards to all those trying to do the right thing
Engines