Earlier quoted context omitted.
Yes, a non-w2 wage earner has income that is not tracked by a w2 ... The general issue with gambling wins is not that the IRS doesn't know (casinos report winnings) its that they don't have to report losses.
What? Casinos don't report all winnings. Anyone can get chips for cash, and cash for chips.
It's generally $600 for winnings, and $5000 for withholding.
https://www.irs.gov/pub/irs-news/at-01-17.pdf
https://www.irs.gov/pub/irs-tege/gaming_withholding_reportin...