I've always thought Star Trek was too much with the America, and it just occured to me readng another thread, two things
1. Why America? what major inventions have come out of there?
You mean besides the sextant, bifocal glasses, the cotton gin, the refrigerator, the coffee pot, the sewing machine, the revolver, the telegraph machine (developed independently but simultaneously with Europe), the safety pin, the first commercially viable typewriter, the motorcycle, blue jeans, the mimeograph, the telephone, the cash register, the electric fan, the skyscraper, Coca-Cola, the hand-held box camera, the escalator, the Ferris Wheel, the gasoline-powered tractor, the zipper, the air conditioner, crayons, windshield wipers, the tea bag, the wirephoto, the Band-Aid, frozen food, the chocolate chip cookie, radio astronomy, the photocopier, nylon, the defibrillator, the aerosol spray can, the microwave oven, carbon dating, the Polaroid camera, the disposable diaper, the heart-lung machine, the nuclear submarine, the polio vaccine, the atom bomb, the integrated circuit, the oral contraceptive, lasers, fiber-optics, the handheld calculator, the product barcode, the space shuttle, the Saturn V rocket and Lunar lander, the graphical user interface, the Hubble Space Telescope, the Human Genome Project?
Well, there's the electric light bulb, the airplane, and the Internet.
Whatever you may think of America, we have a pretty good history of producing major inventions. Especially Ohio -- Ohioans invented the light bulb
and the airplane, and an Ohioan was the first man to set foot on Luna.
Why not Germany or Japan?
Well, one, we have a decent history of invention ourselves.

Two, TOS's Cochrane had an American accent. And three, because it's an American production. You might as well ask why the denizens of New New York in the Year 5 Billion on
Doctor Who all speak with British accents.
2. Was it not unrealistic to have a private scientist like ZC develope Warp Drive with scarce resources after a nuclear war? why not someone like NASA, the ESA or some global UN eqivilant?
Well, NASA, the ESA, and the New United Nations were probably all gone after the war. Having said that, the details of how Cochrane invented warp drive are unestablished; he
was using resources that had once belonged to the United States Air Force. It's possible that Cochrane's warp drive development project began as a government-sponsored project before the war and that he continued it privately after the collapse of the US government during the war. Indeed, that's what the novel
The Lost Era: The Sundered by Michael A. Martin and Andy Mangels establishes.
But it's not that unrealistic -- the history of American invention shows a healthy mixture of inventions resulting from both private (airplane) and public (the Internet) endeavors. And of course American inventions have a history of being augmented by ingenious inventors and engineers in other countries; our friends and neighbors in Great Britain made the Internet a success by developing the World Wide Web, for instance.