The police side of the story was not necessary.

Well, it's a drama. And so they add characters and plot to add to the drama, is my guess. But yeah, it did seem like that aspect of the story didn't much matter, not compared to the family and cartel drama.

Good point about the truck color! So obvious now that you mention it.

They wanted Cooper’s character to drive the theme about family over work. The police scenes added a little suspense. The climax saw him go to prison. It worked better when the audience knows the policeman who takes down our hero.

I too hated the DEA segments...at least for the first half. They seemed boring and pointless up until Cooper started staying at the same motel as Earl, then they became a bit more entertaining.

I thinks it was probably created due to Clint wanting Cooper to be in likely his last movie as they had grown close since filming American Sniper.

Agreed. Each time they came on I read a book.

I think Eastwood wanted the police in the film to explain how cartels work. It did make the film a little long though.