[cateye]

The real problem is the impossibility to define the requirements in a way that they can't be misinterpreted.

We (as a industry) tried it with UML and we found out that it is more work than actually writing the code and it was still useless because there isn't a possibility to check for errors.

Because of this, "the developers" and the "managers" need to reach an agreement on a more emotional level where they can trust each other and fill in the gaps with their expertise and experience.

Just keep on trying to document the requirements more detailed, estimating more factually will be a waist of time and it will lead to bureaucracy and mediocre software.