The people voted for tax on income. Income is passive gains received from owning an asset. Interest is income. They sold it to the people because at the time, only the rich had i come. Everyone else had wages. Taxing of wages was instituted as a voluntary deduction to help the WWII effort. It is still "voluntary". The loophole is that you have to file a tax return by law every year and when you file, you are opted into the voluntary system. Giving false information to the government is also a crime. To this day, there is no statute that says there is a tax on wages. The IRS simply forcibly persuades you to comply by threats of seizure and imprisonment for false statements. https://www.law.cornell.edu/uscode/text/26/7206