Some past threads:
Why American Construction Costs Are So High - https://news.ycombinator.com/item?id=19313042 - March 2019 (158 comments)
Why US Major Infrastructure Construction Costs Are So High - https://news.ycombinator.com/item?id=19308481 - March 2019 (2 comments)
An adjacent one for good measure:
Why Are Canadian Construction Costs So High? (2018) - https://news.ycombinator.com/item?id=21618134 - Nov 2019 (140 comments)