@ShoeBox Taxes "I've seen it in a couple of places, like I said, among them IRS pages."

No, you haven't.  But sometimes the pages blur into one continuous assault by the denizens of Artificial Intelligence world.  "Couple," to me, means "two."  "Among them IRS pages", to me, means more than one IRS page.  Let me assure you that you have not seen it on even one IRS page. 

Perhaps the 40% figure emerged on some report from IRS that noted, "40% of our S Corp audits involve companies that report no shareholder wages."  Because that's what IRS is looking at.  They don't have any method to select returns for audit based on "facts and circumstances" of each owner and each activity, because all that is developed during the audit.  The low-hanging fruit is, "we are coming after you because you didn't report any wages."