See also: companies on eBay selling counterfeit stickers.
See also: the FOP designing stickers almost like vehicle tabs, with color coding so they can see that you're "paid up", sorry, "have donated".
Nothing screams I love my country like blatantly advertising corruption and using a tax exemption to do it.
Just the other day I met someone who was able to open a gun range in a town that I thought would never let someone do it, and he showed me his gold police union card or whatever and bragged about having the state's police union as a customer for his other business via whom he was able to contact an old police boss, and of course they were able to pull the right "levers" to get the permit for the business issued.
https://www.irs.gov/charities-non-profits/other-non-profits/...
The more cops you know, the less inclined you are to get them involved in anything if you can help it. They aren't as bad as game wardens, but still best avoided if at all possible.