Since news broke that the IRS inappropriately audited a variety of grassroots tea party groups, Congress has started a number of investigations aimed at figuring out why the agency engaged in this behavior.

But a bigger question is, why did the IRS target such small, mostly grassroots organizations for audits and ignore massive political players? As the Conservative Intel’s David Freddoso points out, the median income of the groups targeted by the IRS was $16,700.

While the IRS was looking at groups with such a small budget, it ignored the groups with the most money. Here’s the top 3 501(c)(4)s from election 2012:

Crossroads GPS: Karl Rove’s dark money organization spent more than $70 million in election 2012, all of it undisclosed.

Americans For Prosperity:Ai??This Koch Brothers-founded organization spent over $33 million, mostly to attack Obama. It can be assumed much of this money came from the Kochs, but we actually have no idea where it came from exactly because it is not required to be disclosed.

American Future Fund: This pro-Romney group spent nearly $24 million, not a penny of it disclosed to the public.

Following the IRS revelations, there have been calls on capitol hill for increased scrutiny of how IRS grants social welfare tax status to groups. Sen. Max Baucus (D-MT) said that “we need to examine the root of this issue and reform the nationai??i??s vague 501(c)(4) tax laws,” and Sen. Ron Wyden (D-OR) complained that “the lines blurred between [political organizations] and 501(c)(4), and [the IRS has not seemed] to have done anything about it.”