Gotta love it... (not).
M. The provisions of this section shall not apply to law enforcement
vehicles which are owned by the state or a political subdivision
thereof.
That became an issue years ago when it made the news that Oklahoma County Sheriffs cars had tinted windows. People complained and Whetsel was interviewed on the news and said their cars were exempt.
As I understand, the law is on the books, but isn't enforced because officers in the field have no instruments to measure tint levels.