Tony Stark was much more pragmatic, but he acted very evil in the film. He is usually arrogant and egocentric, but he took it way too far. I usually don't like views like Steve Roger's, and like pragmatic protagonists, but Tony Stark took it way too far.

It occurs to me that Tony Stark is a totalitarian and plays politics like Hitler or Stalin. His machine-demon was responsible for a Sokovian holocaust and he simply wants to sign some papers for PR purposes when he will circumvent the rules and break the accords whenever he sees fit; they are frivolous to him. He even flippantly tells Ross that he will put him on hold.

It makes no sense for Captain America to put himself under the command of foreign powers. He barely agrees with the American government, how will he handle answering to his enemies? If anything the American government needs to be put in check for their disaster in Washington and the Hydra infiltration and Tony Stark needs to be put in check because no one was able to charge him with crimes against humanity after his rogue machine decided to have a Sokovian genocide.

Through it all, Tony Stark just wants to play a PR strategy and does not value his "word" like Steve Rogers. He is befuddled and frustrated when Steve and Wanda don't just play along for appearances. He's smart and pragmatic, but also very evil in the movie. He would make another Ultron if he knew it would succeed.

TL;DR: Tony is the more pragmatic one, but he's just trying to sweep the events of his genocidal demon machine under the rug and keep the status quo. He's majorly at fault and in part trying to protect himself and his interests as well as his friends in his own way. The world wouldn't be up in arms about 12 dead from terrorists if it wasn't in the backdrop of Tony's war-crime bot. Captain America is the only one with a moral side, Tony's just on his own side- he's simply surprised because he thought he was on his friend's side too.