Here's one for the Guinness World Records people: Two New York City taxi medallions were sold last month for $1 million apiece. That's the highest price ever paid for the right to operate a car as a taxicab in The City That Never Sleeps. It's also an expensive lesson in the harm caused to consumers and would-be entrepreneurs by overregulation and the strangling of competition. By law, every cab in New York has to have an official medallion -- the numbered metal plate nailed to the hood -- but the number of medallions is fixed at 13,237. When the city...