The issue is that, despite spending more money than any other country by an order of magnitude (excepting maybe the UK) per mile of track, we don't get it done right the first time.

SF's Central Subway which was, at one point, the most expensive rail project (light or otherwise) per mile of track in the world had to get the contractor to go in and completely replace the rails because they had tried to sneak substandard steel past the city.

The megacontractors who build these projects do not deliver quality, they do not deliver when they say they will, and they do not deliver for the cost they bid at. They do make a killing though.