US-American "moguls" don't get killed as often as their Russian counterparts. And even Russia is careful about being too obvious, lest the totalitarian nature of the state becomes common knowledge outside (or beware even inside) Russia...
Now, if you mean "representative democracy" when you said "republic", you'd have a more appropriate question.
The US political system is designed to be rigid against change. Which is mostly a good thing, until, of course, it isn't. But this rigidity is a big strength, and accounts for much of the trust of the world economy in the US government(s).
How to choose leaders and administrators is a tough problem, and I don't have a lot of trust in people who don't actually participate in politics but believe they have a way of choosing leaders and policies that is superior to all the proven ways.
Quite true. I'm not saying the US is bad. I'm just pointing out that it's not some kind of anointed perfection.
Equally damning is the media control.