There seems to be a weird attitude in the US that the police are some sort of independent entity, and the most the state can do is reduce its tribute to them. This is a really odd approach, and doesn’t really have a parallel elsewhere; successful police reform had generally involved changes of leadership, independent misconduct commissions, and increased consequences.

They are usually unionized. This mandates that many changes opposed by the union (misconduct commissions and increased consequences) would have to be approved/negotiated by them or else risk a strike. Those negotiations tend to cut out any meaningful changes that threaten their autonomy/privileges.