Because almost everyone who purchases anything pays 'sales tax' and almost all homeowners pay 'property tax,' but the problem we care about is income/capital gains tax evasion.
If that’s the problem that is cared about. Are you saying going after the lower socioeconomic class of America is how to get back those evaded taxes?
The narrative in general for the statistic is about lower socioeconomic people. If this was a good faith caring about tax evasion. Why would the focus be on the people with the least income and wealth?
I don’t think it would be if that was really the problem being cared about.
And yes the sales tax is part of the point. To give nuance to such a simple statistic.