Wendy's called the cops because he was asleep in his vehicle in the Wendy's take-out line and other patrons could therefore not place their orders. So he was drunk driving, or DUI as he drove himself to the Wendy's while intoxicated.
You should watch the video. It is 43 minutes long, but it shows a mostly friendly interaction. It also makes really clear that Mr. Brooks was drunk.
I think once upon a time, officers would not necessarily throw a guy in jail but give him a ride home after taking his car keys but that's changed in recent years with MADD and others pointing out the dangers of drunk driving. Officers are just a lot less tolerant of DUIs.
The reason the officer shot Mr. Brooks was because he stole the taser and tried to use it on the cop.
If he hadn't stolen the taser, I doubt he would have been shot. But I don't know. Cops do tend to react more harshly with black suspects, which is not fair.
But until Mr. Brooks hit the cops and stole the taser, the interchange between them was amicable. So none of that needed to happen. It's really sad, because now there are kids growing up without their father, and that happens way too much in the black community.
Anyway, this is all just my opinion and I am fine with disagreement. One thing I am not denying is that blacks do still deal with unfair racism and it's not right. Black lives do matter. And we do need to create a more equitable society for everyone.