Here's another example. As dissatisfaction with government schools increases, some parents, especially minorities, seek more responsive alternatives. This threatens teacher unions. Hence they mobilize to thwart school choice initiatives. Silicon Valley's Tim Draper invested 20 million dollars of his own money on a school-voucher initiative but was badly beaten by the education establishment.
Teachers unions enjoy their monopoly and invest to protect it.
Organized interests look to government to protect them from, or compensate them for, the consequences of such threats. When government controls or biases outcomes, buying political influence is a rational investment of mobilization or money. In this context, it is nearly as silly to expect meaningful campaign reform as it is to complain about the force of gravity or friction of air. When governments allocate values, people compete to influence that allocation. Only the means of influence will vary.