Not exactly a case of 'not speaking up'
The problem is, often people DO speak up, but they get overruled/ignored by the management who firmly believe it's the right thing.
I work in IT and I see it all the time. The management come up with an idea, they put it forward, the costs are high, the timescales more so, and everyone on the IT team says "this isn't going to achieve what you want" - the amount of times I've tried to say that and have been politely told "I hear you, but we're going to do it anyway".
Then (of course), when these things get canned the IT team gets the blame for large costs and long time scales.