In a review of John J. Mearcheimer’s Why Leaders Lie the following is noted:
The leaders most likely to lie are precisely those in Western democracies, those whose traditions of democracy perversely push them to mislead the very public that elected them. In fact, Mearsheimer says, leaders tend to lie to their own citizens more often than they lie to other [governments]. Review by Carlos Lozada, John J. Mearsheimer’s “Why Leaders Lie” The Washington Post, April 15, 2011.
In Blame Victims For Lies, Robin Hanson had the following take:
Since gullible people tend to believe what they are told, other folks are more tempted to lie to them. So if one chooses to be gullible, one must accept a lot of responsibility for the lies one hears....
Much of that gullibility seems to me to be by choice; people seem to see themselves as good people if they give their leaders the benefit of the doubt. Then they express righteous indignation if they discover that their leaders lied. But really, they are themselves mostly to blame.
I am not sure about the universality of the outrage. We tend to choose sides, and only get mad when the other side is caught in some sort of lie. The excuses you see to justify the lies of ones own side can be pretty amazing.
I would argue that democratic leaders lie more because the system forces them to be more accountable to their constituents on a more frequent basis, and often they have a broader range of constituents.
People, in general, lie a lot. When they are placed in a situation of where there is an inequality or asymmetry of information or knowledge, you tend to see a lot of lying. For example, in construction specialists often have unique knowledge about pricing and methods. They have an incentive, and the system tends to work toward reinforcing that incentive, to use that information to their advantage.
Since the world is a big and complicated place, and most people would rather not take the time to learn much about it, there is an advantage to feeding them dross.