One obstacle is the current system has diffuse costs but concentrated benefits. A much simpler tax system would be one in which many accountants would no longer

One obstacle is the current system has diffuse costs but concentrated benefits. A much simpler tax system would be one in which many accountants would no longer be needed. They're enjoying the concentrated benefits and thus their incentive to protect the status quo is much higher than the incentive of everyone else to change it. They're also facing a loss, which people generally perceive as a more intense event than a gain of the same magnitude.