As I have said before, the US system is a amalgum of all possible systems you can imagine. What works for the Army Corps of Engineers does not necessarily work elsewhere. We try what looks best and change if it doesn't work. We have a "whatever works" system where people can buy, sell, consume and produce the best way they can. Clumsy, sloppy, inefficient, slow to change and imperfect, it still produces 40% of the world's wealth and the US is the #1 dream of emmigrants from all over world. We also accept more new people each year than all other countries combined.