>I tend to think that the lack of openness is done on purpose

I doubt it. From my experience it's from outsourcing development to too many different groups with no coordination.

I worked on interfacing with a BigName's Hour Time Tracking module which takes hours to 8 decimal places. I submit the first payroll and hear it is imported with no errors.

Two days latter I get a frantic email asking me to resubmit because the Payroll module only takes 6 decimal places and was throwing out all the submitted hours. The systems are so large the consultants themselves cannot possibly understand it, let alone provide proper documentation.