Earlier quoted context omitted.
yeah I was not too convinced when I read the article. The government can easily figure out the taxes for your wage (which your employer did actually figure out) but they can't figure out the taxes on your real estate revenue, and maybe other activities (traded cryptocurrency? freelanced on the side? Airbnb"ing" some of your estate)
I would be willing to bet good money only a tiny percentage of people have income outside their employment. People who have real estate or bitcoin profits could always file an andendum.
https://www.irs.gov/uac/soi-tax-stats-individual-income-tax-...
There are numerous other ways to have income outside of formal employment in the US. The most salient one for tax purposes is self-employment.