It's the market at work, and to a certain extent it relates to the spread of chain restaurants and chain stores. People want a certain amount of variety, and the presures of the market force people to find a successful formula to work with instead of reinventing the wheel. Thus you get McDonald's and Burger King and Wendy's in place of all the little mom & pop diners, because as franchise owners they can tap into a purchasing network that gets them the lowest prices on beef, chicken, fish, and veggie patties along with all the other starchy sugary goodness on the fast-food nation's menu. (For that matter, down home there's even a chain of diner-style restaurants for folks that want that kind of experience.) Ditto for Mexican food, ditto for seafood, ditto for steak, in a variety of market niches that cater to everyone from Joe Sixpack to Rush Limbaugh.
The same is true of gasoline - the number of independent refiners and oil companies has been squeezed down until there's only a handful of major gasoline chains left, since it doesn't make a whole lot of difference to most drivers whether the gas comes from BP, Chevron, Exxon, SuperAmerica, or the handful of mom & pop places left that buy their gas by the tankload from Valero, which has the lion's share of the refineries these days. Cobb's wrong about gasoline on the national level, by the way - because of EPA regulations and state laws, 90 octane midgrade in Iowa isn't the same as 89 octane midgrade in Virginia, but since the differences are between regions they're pretty much invisible to the average driver.
By and large, mature technologies are a lot simpler to operate than new, bleeding-edge stuff, but they do have some complex production requirements behind them. Wal-Mart's low prices come at the cost of a significant investment in complicated supply-management software; the failure to acquire or develop that software eventually killed K-Mart and drove it into the arms of Sears. Jury's still out on whether that merger's going to work out in the long term or just put off the demise of both companies for a few years. Meanwhile, not everyone shops at Wal-Mart, either because the clothes are too cheap or not stylish enough, and that's why Target is still around, to say nothing of the other dozen or so clothing stores that cater specifically to teenagers, white-collar women, and yuppies. Complexity.
Speaking of mature technologies and market niches, I wonder if somebody besides Nissan will take advantage of the fact that Ford and GM are shuttering a lot of plants and laying off workers. It strikes me that people might be willing to pay a little more for custom cars built to order with chassis and drive trains from Chrysler, GM or Ford. Saturn, Kia and Hyundai showed that the market is open to new makes of cars; is it all that unrealistic to think that Packard and Studebaker might make a comeback along with other vanished companies?