Why does the Republican party seem completely unable to say anything except trivially obvious lies and bullshit?
Because it works.
No one with any political or economic power has any interest whatsoever in telling the actual truth; there are only differences of opinion between capitalist factions about what sort of lies to tell. The Democrats tell "it's all going to turn out right in the end" sort of lies; the Republicans tell "you're all fucked, might as well lie back and enjoy it" sort of lies.
The truth has ceased to matter, and nobody, neither the powers-that-be nor the people, gives a rats ass about what Ophelia and Jeremy think.