Plenty of people use them. They can be issued "en masse" for multiple workers. It makes sense to hire a law firm, it's the government after all. Just for fun I checked the website of a local law firm. Their link to the Nebraska INS which handles Illinois indicates they're currently processing applications dated 8/10/2006. Obviously there's time involved in preparing the application. In my view growers planning for the 2007 harvest have plenty of time to comply with the law.
The problem is not time-to-issue. So few are issued they can be processed quickly (well, by INS standards, or whatever they're called these days). The problem is the restrictions are so onerous that the visas are useless - which is why so few are applied for. The links explain that.