The higher-than-Europe comparison I had not heard before. The higher than private industry cost of United States government contracting (and contracting by local units of government when they spend federal funds) is dictated by the Davis-Bacon Act,
http://www.dol.gov/whd/govcontracts/dbra.htm
once we understand that the law's requirement to pay "prevailing wages" means, in that context, to hire union labor even when less expensive nonunion labor is available.
This article discusses some examples: http://www.theatlanticcities.com/commute/2011/11/1-billion-d...
Madrid comes in at $58m/km, Paris and Berlin at $250m/km, and anything in the USA at over $1 billion per kilometer. NYC at $1700m/km. Some of those differences have legitimate explanations, but that's a 30x difference between Madrid and NYC. The Copenhagen metro, with quite expensive Scandinavian unionized labor, also cost a mere $150m/km, and the current expansion seems to be clocking in around $200-250m/km.
According to the Wikipedia[1], the 1318 km Chinese Jinghu High Speed Railway (350 km/h) came in at about $27m/km.
The french LGV Est, also rated for 350km/h, cost ~€4b (up from an original 3.125m estimate, excluding trains) for 300km[0], or ~€13m/km -> $~17m/km. Including all costs (trains &al) according to the 2007 SNCF report the line cost €5.5b, €18m/km, ~$24m/km.
(Not arguing with your basic premise that US costs are over-expensive, but a lot of that 30x difference can be explained away).
A bit of it can be, the 5x difference between Madrid and Berlin/Copenhagen/Paris seems acceptable by the differences in environment (Copenhagen's lowest point is 1m above sea level) and costs of living or complexity of the city's "cellars". The 6x increase on top of that is harder to justify.
http://www.telegraph.co.uk/news/uknews/scotland/9345650/No-s...
About £1 billion for a tram line where the end points are about 11 km apart in a city that has excellent taxi and bus services....
[NB We will have a spare aircraft carrier going "cheap" as well...]