06/18/2014 04:57 pm ET

Stop Telling Rich People To Give More Money To Charity

John Lund via Getty Images

By now, the Walton family, the nation’s richest through its ownership stake in Walmart, must have developed a pretty thick hide. They have long been subjected to intense criticism regarding the massive retailer’s allegedly exploitative labor practices. But this month, they absorbed a blow at a particularly sensitive spot: their philanthropic self-regard.

In a report entitled “The Phony Philanthropy of the Walmart Heirs,” a union-backed group, Walmart 1 Percent, argued that the enormous size of the Walton Family Foundation -- it can claim total assets of $2 billion and was recently ranked as one of the top foundations in terms of annual giving -- should not be taken as a measure of the family’s generosity.

Nearly all the foundation’s resources come from a handful of trusts set up with assets provided by Sam Walton, Walmart’s founder, his wife Helen, his son John, or their estates.