While I appreciate the level of nuance Post 3 adds, the problem with PACs is that the amount of money spent could determine the amount of influence. So rather than making our public policy decisions based on an honest weighing of interests, we simply acknowledge who can raise the most money. It has always been a reality that American politics (and all politics) is controlled by those in positions of wealth and power, and PACs in many cases contribute to this. 

Looked at in a more positive view, it can be difficult for legislators to ignore the PACs because the PACs actually do represent real people.  We tend to think of them as "special interests," but we fail to realize that those "special interests" are made up of real people with political opinions that deserve to be heard.  So one reason it's hard is that the PACs can mobilize voters who care about their issues.

This question about legislators ignoring the wishes of PACs is a terrific question at this time when campaigns for election or re-election are in full swing.  In my opinion, the reason legislators will find them difficult to ignore is the huge amounts of money it takes to be elected. . Campaigns cost obscene amounts of money and right now, PACs influence legislators by pouring money into the candidate's campaign or by paying for advertising which supports their campaign or ideas. Conversely, a PAC can also work to defeat the candidate and support the opponent.   A PAC or Political Action Committee wields influence in states far from their own because of the advertising they pay for to support or defeat a candidate who is in line with their views.  For me, it feels way too much like buying an election because there are so few controls on the money needed to run for office. Election money too  often influences legislators to support the wishes of PACs.