Gaping wound that lifted billions out of powerty and produced the greatest standard of living in human history.
Corruption mainly exists because people have low standards for enforcing eradication of it. This is observable in the smallest levels. In countries where corruption is deeply engraved, even university student groups will be corrupted. Elected officials of societies of any size will be prone to put their personal interests in front of the groups' and will appoint or employ friends instead of randomers based on some quality metrics. The question is what are the other people willing to do? Is anyone willing to call them out? Is anyone willing to instead put on the job themselves and do it right (which can be demanding)?
The real question is how far are the individuals willing to go and how much discomfort are they willing to embrace to impose their requirements, needs, moral expectations on the political leader? The outcomes of many situations you face in society (should that be a salary negotiation or someone trying to rip you off in a shop) depend on how much sacrifice (e.g. discomfort) you are willing to take on to get out as a "winner" (or at least non-loser) of the situation? Are you willing to quit your job if you cannot get what you want? Are you going to argue with the person trying to rip you off? Are you willing to go to a lawyer and sue them and take a long legal battle? If people keep choosing the easier way, there will always be people taking advantage of that. Sure, we have laws but laws also need maintenance and anyone wielding power needs active check! It doesn't just magically happen but the force that can keep it in check is every individual in the system. Technological advances and societal changes always lead to new ideas how to rip others off. What we would need is to truly punish the people trying to take advantage of such situations: no longer do business with them, ask others to boycott such behaviour (and don't vote for dickheads!, etc.) -- even in the smallest friends group such an issue could arise.
The question is: how much are people willing to sacrifice on a daily basis to put pressure on corrupt people? There is no magic here, just the same bare evolutionary forces in place for the past 100,000 years of humankind.
(Just think about it: even in rule of law, the ultimate way of enforcing someone to obey the rules is by pure physical force. If someone doesn't listen, ever, he will be picked up by other people and forced into a physical box and won't be allowed to leave. And I don't expect that to ever change, regardless of the political system. Similarly, we need to keep up an army at all times. If you simply go hard pacifist, someone will take advantage of that... Evolution. )
Democracy is an active game to be played and not just every 4 years. In society, people's everyday choices and standards are the "natural forces of evolution".
But most of the world doesn't work like that. Countries like China and Russia have dictators that steer the car. Mexico have gangs and mafia. European countries have parliamentary democracies and "commie journalists" that do their job and reign political and corporate corruption--sometimes over-eagerly--and unions. In many of those places, wealth equals material well-being but not overt political power. In fact, wealth often employs stealth to avoid becoming a target.
USA is not trying to change things because people are numbed down[^1]. Legally speaking, there is nothing preventing that country from having a socialist party win control of the government with popular support and enact sweeping legislation to overcome economic inequality somewhat. Not socialist, but that degree of unthinkable was done by Roosevelt before and with the bare minimum of popular support.
[^1]: And, I'm not saying that's a small problem. It is not, and the capitalism of instant gratification entertainment is entirely responsible for this outcome. But the culprit is not capitalism at large. IMO, the peculiarities of American culture are, to a large extent, a historic accident.
A smart dictator is probably harder to corrupt, but they die and then if you get unlucky with the next dictator the car will crash and burn.
Mao and communism brought famine and death to millions.
The move from that to "capitilism with Chinese characteristics" is what has brought about the greatest standard of living increase in human history.
What they're doing now is a mix of socialism, capitilism and CPP dominance. I'm not an American, but I understand FDR wielded socialism too, and that really catapulted the US towards its golden era.