Because it's a democracy with a very well established bureaucratic epidermis that stretches from federal to local level. It's a vast and complex entity that operates on defined rules.

Until trump, the infection of fickle, cynical politics never made it very deep because the folks operating in that bureaucratic layer were career people with operational ethics (and frankly were quite boring-- by design), not nominated people. The sycophants are purging those people now. The rot is making its way deeper into the inner workings of the country like a cancer.

Now they're not afraid of lying because that's what their rulers want them to do. Do whatever it takes to make the boss look good or suffer the consequences. That's the kind of behavior you expect from North Korea. Not the USA.