There are three kinds of ‘average’, Mean (arithmetical average), Median (midpoint of the distribution of the population) and Mode (most frequently occurring value).
$50,000 by any reasonable reading would seem to me a halfway mark, the middle, half above, half below.
So you are saying he is basing that stat on the total number of taxpayers?
I have no idea where Rush got this data, but it might be taxable income. Most people making $50k don’t make anywhere near 50k taxable. You have off the top deduction, then kids, then perhaps mortgage etc.