As an outsider, it feels to me like the budget of any project tends to expand to the amount of capital available. When the budget is less, people tend to be more frugal. Which also means that at least some corner-cutting is done. But when the resources are vast, people insist on doing everything by the book. I see this not only in cases of public infrastructure but also in case of space programs as well(case in point, Mangalyaan). America has always been resource-rich and therefore I observe that it has a culture in which spending a lot of money is acceptable(since there is a lot of money).