well Mitch, I would have to say that a person is not required to "step out of the vehicle" upon request all the time. regardless of the circumstances, the police had no cause to shoot the guy for failure to follow their requests. we have a right not to cooperate with the police in their investigations, its called the 5th amendment and exercising ones rights is not cause for the police to use force of any kind. if they wanted to arrest him, then why not break the window, open the door, and pull him out and arrest him? they did not have to use deadly force. 

use your common since, is there a valid reason to exit the vehicle? are you stopped for a ticket? then write the darn ticket and let me be on my way. I don't have to cooperate to the point of engaging in a conversation to answer questions, or exit my vehicle. if they inform you that you are under arrest, well then you might cooperate and allow them to detain you.