This is definitely true in some places. I have worked on Defence contracts that worked in exactly that way - win the initial bid by being cheapest, and then hav

This is definitely true in some places. I have worked on Defence contracts that worked in exactly that way - win the initial bid by being cheapest, and then have the MOD pay you to fix all the bugs later. OTOH, it's not the culture where I work currently. We are expensive, we know we're expensive but the reason we can get away with it is because we deliver. That's on several fronts like technical capability but also because when we say "It'll cost X to get you what you want" it usually ends up costing them something close to X. Part of doing that is that if we don't have enough information to build the thing, we might do a "Phase zero" for a fixed period of time looking at the biggest question marks and that means we're much better informed to quote the main piece of work.