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.
(..) You buy four tires, I give you a full-a size spare - absolutely free! - Look, I get all my tires for free. I like your style, eh? You drive the hard bargain. OK. Luigi make you a new deal. You buy one tire, I give you three for free! Oh, would you look at that? Ramone, Ramone! (..)2006 Cars