He hadn't 'bargained on' how his new position in the company would change the way people treated him. [=he was surprised by how his new position changed the way people treated him]
You're allowed to go to the football game tonight, but I expect you to 'keep your side of the bargain' [=do what you agreed to do] and clean your room.
They've agreed to turn the land over to the state, and the state, as its part of the 'bargain', has agreed to keep it undeveloped.
(..) one was attached to his favorite. You don't have to do it just because he tells you. What choice does she have? / He's not gonna hurt us. He needs us. Why? / To bargain. He'll hurt us alright. Do you think he's coming to the Green Place? He's a crazy lunatic who likes to eat schlanger! (..)2015 Mad Max: Fury Road