Steve and Wanda shouldn't have been there to begin with. There's no reason they couldn't have notified local law enforcement and let them handle it, or at least evacuate the area instead of going to a foreign country and performing an unauthorized paramilitary raid. I thought it was insane that Steve actually said, "The safest hands are our own" after causing the deaths of all those innocent civilians.
As for Wanda blaming Tony for her parents' death, if you got shot who would you blame, the person who fired the gun or the CEO of the company that made the bullet? If the bomb had been o