Other than the reasons already pointed out, money plays a huge role in elections in the U.S.A. Without large influx of money, a politician can not run an effective campaign - hence corporations have a huge leverage. To put it bluntly: corruption is rife in the U.S. but it is "hidden" as money does not (always) go directly to a politician's pocket, but it is diverted to his/her campaign. What the U.S.A. needs is to revamp its law and limit contributions to small amounts per person - including corporate persons - and reverse the Citizens United ruling through a constitutional amendment.