In terms of mathematics textbooks, why can't you have the scale of a national market? Right now, we have a Texas textbook that's different from a California textbook that's different from a Massachusetts textbook. That's very expensive.
If you have 50 different plug types, appliances wouldn't be available and would be very expensive. But once an electric outlet becomes standardized, many companies can design appliances, and competition ensues, creating variety and better prices for consumers.
