Here in Florida there are a number of people with adhesive badges stuck to their license plates that identify them as affiliated with a police association. Now, I've written before regarding a theory of optimal stranger information. But what if there's more to these police association stickers than just optimal stranger information? What if they are costing me money? What if they are endangering my life?
First: the money angle. These stickers are a form of rent-seeking. Assuming police cannot pull over EVERYone violating traffic law, they must pick among myriad offenders. These stickers are designed to ingratiate the driver with the police, thus reducing the likelihood the driver is stopped. But this increases the scrutiny I will face, since I don't have one of these stickers, and with increased scrutiny comes increased expected value of fines. ("Hey, A Random Stranger, just don't break the law and you'll be fine!" We're well beyond that now, ignoramus.)
Why don't I just get one of these license plate medallions on eBay (one's available now for $38)? Well, besides the fact that, ironically, THEY ARE ACTUALLY ILLEGAL, I'm opposed to the things on principle. The correct response to the growing kleptocracy is to oppose it, not to join it.
Second: the safety angle. Earlier this week, Scott Sumner blogged about a law of conservation of bigotry, which would say that we have a natural human tendency to see things along an in-group/out-group divide and when we break down one sense of the out-group, we have to create a new one to replace it. With the increased media attention to violence targeted at police officers, a growing number of police officers would come to view non-police as members of the out-group. (Think of every criticism of the "black lives matter" movement and ask how they apply to the "blue lives matter" movement.) As bigotry towards the out-group increases, the possibility of using violence against the out-group would increase, as well. Thus, these medallions help create a world where police are protecting themselves and members of their in-group by subjecting us members of the out-group by whatever means necessary.