No offence intended to Americans, but those guys are culturally much tougher negotiators than us. When they know they have leverage over you they don't hold back at all. We get caught out by this over and over again because we speak the same language so we think we understand what's going on, but we aren't awake to the nuances.

You might want to google Tizard Exchange for what happens when the US has us over a barrel. Or look at the outcomes of pretty much any attempt to extradite an American citizen vs US attempts to extradite a UK citizen.