There was a micro-story in the news this week about a new tax imposed on tanning salons. The 10% tax is supposed to generate $2.7 billion over ten years to help pay for the Obama health care legislation. Why tax tanning salons? Because tanning is related to skin cancer, so it ought to be discouraged by taxation. Everyone knows that whatever is taxed is discouraged, right? But when the revenues from the tax are calculated, the assumption is that there will be no effect, so revenues will be reaped as if no one is deterred. That’s the way tax revenues are usually calculated, which explains why there are usually shortfalls. These days, having computers and such, revenues ought to projected taking tax avoidance into account.