Faeylyn,
I have read (from several different sources) that the orginal law was intended to provide tax relief for farmers. Of course people of other occupations could also take advantage of the law, as long as the rules pertain to them. But from what I know, the original law was to help farmers.
The reason that this tax law becomes a loophole is because a lot of people are taking the deduction that do not really qualify. Big, heavy SUVs used for personal use were not nearly as popular as they are today when this tax law first went into effect. The tax law may still be legitimate, but a lot of people are using it as a loophole.
Anyone can become an instant entrepreneur these days by simply registering a business as a sole proprietership and using his or her social security number as a business tax number. Then he or she can buy one of these SUVs, use it for business, and take a fat tax deduction. This was not the original intent of the tax law, so it becomes a loophole.
You know as well as I do that "proving" the use of XXX amount of miles is almost impossible, whether it be legitimate business use or personal use. This is exactly why we will soon see big changes to this tax law, especially with the recent popularity of heavy SUVs.