Follow the money. Cop unions do not want people that can defend themselves, never mind that police cannot, their is an illusion of safety. Responsible people who find they can take care of themselves may demand that we need less police, which means less dues.
Simply put, it's good for business.
The ASA is an entity that should not exist in the capacity that it does. Through some hook, crook, and legislative act, the dues of the members of ASA may be paid using public monies from the sheriff's office funds the local county commission, or another source spelled out in the Title 45: Local Laws. However, ASA acts as a lobbyist or retains a lobbyist, and frequently opposes anything to do with changes to pistol licenses or permits (an all important source of revenue for sheriffs) as well as other measures in a decidedly anti-gun, anti-citizen manner. Properly applied, since the permits are effectively issued by the state, the state should be printing them, managing the information database associated with them, and the funds for said permits should flow into the General Fund of the state treasury. If the sheriffs require more money than they are apportioned from the various funds and sources of the state, they should talk to the legislators to see about getting apportioned more money or apply for and receive grants or donations.
The essential bias of the ASA and FOP are that there are three classes of people: The people who hire LEOs or have money, power, or influence that can get things for LEOs, the LEOs, and people who aren't LEOs. Never forget that the people in the first set are in the third set. For further reference, look at the recent Bentley scandal, how Spencer Collier fit into the debacle, and how he -- a manager who was once an APOST-certified front-line officer -- effectively has done no "police work" since he was promoted to management. Yet, he carries a badge and a gun, and will likely keep them in retirement.
This follows remarkably closely to the feudal era, where "The Knights Of The Roundtable" enjoyed a right to bail and to be released into the comfort of six of their peers following an arrest. They didn't have means, but they had physical strength, armor, and arms.