I disagree.
I think just because americans are fond of their lie-detecting machine, doesn't mean that every other culture envisionable would use these marvelous devices in a fantasy world.
Ask yourself the question: "Why isn't the use of the lie-detecting machine more wide spread in the world today?"
The answer of course is that it is unreliable, and it can be beat.
In the fantasy world, there are ways past the common
detect lie spell. Or should this only be the previlege of the very rich?
How many priests does the justice system have at their beck and call to cast constant
detect lies in every court case? Who reimburses them their expense? Who vouches for the priest's honesty? Who watches the watchers?
If I build myself a lair to hatch "Evil plots" (TM), I want myself and my closest plot-hatchers near me, in a secluded place, insulated from would-be do-gooders. So I have the toughest, most loyal muscle near me, as body guards, and out front I have the two-bit goons.
I would go on, but lunch calls, so maybe after lunch
To me the biggest problem is the abundance of Humanoids. How many intelligent bipeds can there be, all competing for the same resources?