If by 'we' you mean 'people educated in Britain', I'm not sure they are: don't British Project Managers oversee countless successful projects all around the world, and not a few at home? Maybe the problem lies with the client...
You probably have hit the nail pretty well on the head there. On Wednesday evening I went along to a local Wiltshire Council meeting to hear the latest on the "Melksham Campus". I first got involved in March 2011, and spent a great deal of time - along with 9 significant local community members - over the following two years, and at the Council's request and with their support, working out what was needed. Our budget was clear and fenced, our objectives were clear, and between us we reckoned we put in 8000 man-hours. A very interesting exercise, balancing the demands of groups who pushed strongly for more than the really needed (or could be expected to use) against those who took a much more conservative view. Planned initial use, September 2016, finished (e.g. removal of old swimming pool) over flowing winter.
We were warned as we went through this process that we needed to get it right first time, bearing in mind the cost of architects, highway engineers, planning, officer's time, etc (we were volunteers, but I really don't think those who were doing those other elements were 'free'.)
Then ... heed my words ... extra elements ranging from police to post office to a doctor's surgery were added. And with them came changed specifications - not only the space but "single reception" changed to "need multiple entrances" as the idea of having the police haul someone in handcuffs past the schoolkids on their way for a swim
Then ... the council decided, with the steering group's vetting or approval ... that the Rugby and Football's new facilities would be a huge expansion on the current facilities, and on a new site ... and suddenly a third of the budget, and four time what we had expected, went to that. It may have been the right decision, but without visibility I remain doubtful. There's a suggestion with the numbers as presented that the council may have sold
itself the land for the rugby and football - thus pulling money out from the fenced budget into other council pots - double-dipping might be the term.
And ... guess what ... the community group is then told it's over specified the building, got elements of it wrong, and is being reduced to a much more advisory role ... it will be called together again when it's advise is needed and that has been never.
So - on Wednesday, we went along to see new plans that Wiltshire Council have submitted to Wiltshire Council. Even there, there are elements "at the last minute we have consulted with the public and as a result added ...." swimming pool seating which we knew about 7 years ago, for example. Completion planned for 2021. Looks very different. The public facilities that the site was all about are now to be shared with residential accommodation "to help pay for it all". We are assured the budget is unchanged. Maybe; I probably can't tell you the amount still - but by the time you look at so many cycles of planning and working out, dipping money out to buy land you own already, and the rest, I would not be surprised if the spend on the Campus facilities themselves is less than half of what was planned - somewhere in the order of 40% in fact.
Yes, the volunteer group can hold its head high, even though accused of a lack of prudence. Moving goal posts, problem with client!