Sasless, I can only speak for Europe having been fortunate never to have ventured into Africa etc, but your question is along the lines of "when did you stop beating your wife" ie a presumption that there have in fact been "unfilled vacancies all along in most of the business units". In Europe, this is certainly not the case, in typical oil industry style we have cycled between having too many and too few pilots in accordance with the cycling demand for our services. For most of the time until recently, there have been no unfilled vacancies in Europe, something which our African workers bemoan when they try to get back to UK.
Perhaps there has been a constancy of unfilled vacancies in Africa, but there are good reasons why that is so! I am certainly glad we don't have managers who "work towards creating long tenured, cross trained, qualified and experienced crews" if that means I would have to do a stint in Nigeria!
But you are right in part - one of the features of the Business Unit structure is that its every BU for itself, and that kind of clashes with the "One world, one team" mantra!
Anyway, you have been out of the company for a long time and I think you would find that your bitterness is less warranted these days.