The answer is one word: permitting. A highway in the US requires a NEPA environmental impact statement that takes an average of 5 years to prepare. That's before anyone pours concrete. Add design, land acquisition, utility relocation, and public comment periods and you're looking at 7-12 years from concept to cars driving on it. A bridge replacement in the Northeast can take 4.5 years just for the environmental review. A data center? 18 months from breaking ground to servers running. Some…