[mszkoda]

It is exactly this.

You look at donations to people from corporations or through lobbyists and they don't look that large, $15-20k and they are getting big bills passed.

That $15-20k isn't buying the politician or their vote. The threat to give millions of dollars to the opposing politician that will support them is.

[JMTQp8lwXL]

There are limits on how much you can donate to a candidate's campaign; however, you can contribute unlimited funds to a PAC, but the PAC's advertisement efforts must be separate from the candidates; they can't be coordinated.

[cortesoft]

Which is perfect for a company like TurboTax who wants to lobby for an issue... they don't care about the candidate, they don't have to coordinate with them at all... they just tell the representative, "if you don't vote my way, we will fund a PAC that will attack you". No candidate coordination, no problem.