This Reason.TV video pokes some serious fun at state laws requiring interior designers to be licensed in order to work or, more often, in order to call themselves "interior designers" rather than decorators. The attempt to justify such laws as consumer protections is lame. The video sums up the obvious motive behind them in a pithy quote: "You make more money if you have less competition." Ah...the glamour of restraint of trade.
Over the past decade or so of observing designers of all sorts, however, I've come to believe that there's more to the lust for licensing than pure economics. Designers crave respect--note the video's derisive references to throw pillows, even as it makes the case that good interior design requires talent and experience--and many imagine that a license will buy it for them: Hey, I'm a professional! Even if it doesn't, more money makes a nice consolation prize.