Its a safety issue for the officers out there apparently.
This has always been a bulls*** excuse for the municipality to generate revenue beyond taxes. The reason it's bulls*** is that certain vehicles (SUVs, vans, limos) are exempt. What, only people in passenger cars are capable of pulling a gun on a cop whereas SUV occupants are always law-abiding citizens? It's because celebrities/politicians/dignitaries don't want to be spotted while being chauffeured around town. If every type of vehicle was subject to tint laws, I wouldn't have a problem with the safety excuse.