The IRS is trying to capture previously hidden business activity but they have cast a very wide net.
Basically, all your business income must be reported, even if you don't get a 1099. On the other hand, if you get a 1099 for personal activity, just getting a 1099 does not make it automatically taxable, but the IRS will want to see an explanation. (Some types of personal activity, like hobbies and casual sales, are taxable even if you don't engage in regular activity that could be classified as a business.)
