Decision making in almost any organzation has to be a political process. This is true because any leader has to have the support of his subordinates if a policy is to be carried out properly.
This is true even in organizations where the leader supposedly has complete power. If he does not build support for his decisions, the subordinates may be unenthusiastic about implementing them and may do so as slowly as possible.
At lower levels of an organization, decision making is political because every person involved in a decision will be looking at the decision in terms of its impact on their future chances for promotion.