The problem is, governments and politicians look at "maegaprojects" as a badge of honor that they can tell people that they were responsible for getting them built (and "improving the area" as well).
Here's a great example from Buffalo:
http://www.buffalonews.com/city/communities/downtown/article886496.ece
Here we have a $300 million building built by the University of Buffalo. We can discuss whether this building is needed at all, but even if is needed, look at the photo. Why is a four-story atrium needed? Custom-made glass? This building could have easily been built for half, or even a quarter of the price. But, it's an "important" project that improves "education". And god forbid that you "oppose" education!