I think you're strawmanning a bit. They're not saying poor people are tax cheats, just that tax cheats tend to be poor. This makes sense for the same reasons other types of crime are also associated with poverty. This is not to say that wealthy people do not also evade taxes, but they do so in ways that are harder to catch and prosecute. You're implying that going after poor people is some sort of classist discrimination but I think it's far more likely that there are good reasons for it.
am i missing something, or is the statistic that is used to pinpoint someone as poor, is the same statistic that is gamed here? Namely the amount of income that a person declares to the IRS?
Or just that there are more poor people. Say 10% of all people are tax cheats, evenly across income. The top 1% who are the rich is much smaller than the bottom 50% who are the poor. So in absolute numbers there will be far more poor tax cheats than wealthy. Even if 100% of the wealthy are tax cheats, that still ends up being fewer wealthy tax cheats than poor tax cheats. Anything involving absolute numbers of audits is going to be skewed to show more happening to the poor, because there are so many more poor people than rich people.