The information they're using is also based on tax returns, and musicians are way more likely to not report their full earnings than, e.g., someone who works for a company and gets paid salary with normal withholdings. Unless you're a huge touring musician playing to thousands, you're usually getting paid in cash or checks that are below the 1099 requirement level.
Just because you don't get a 1099 doesn't mean you earned that income tax free. It still needs to be reported and people are breaking the law if they don't report it as non-1099 income.
Oh I'm fully aware it's income tax evasion, I'm just saying that, realistically speaking, a lot of people tend not to pay taxes when on unreported income.
