Doesn't it seem as though no government can function in the people's interests once the population exceeds some certain number? Also it seems that a government loses its goodness after a certain time period. It seems to me that a system that might work is to limit the number of people any government serves, and have two or more types of government and swap the one being used every so often, then when one starts up again it goes back to its original form. Careful note might be made of any changes during its use that proved beneficial.
You might ask, "Noted by whom?" and the answer is that everyone has to be alert and take part, and the responsibility is shared by all. If people don't care then it all slopes back to a lousy system.
Younger countries have a certain vigour that could be artificially recreated in this way. As time goes on a country with the same system accumulates errors and the corruption pulls it to one side like a car with a bent axle.
I just don't think any government can work for huge populations. I'm not sure what the optimum number is. I feel the ponderousness of the system acts as a prism for errors. Australia has a population of something like 23 million. That seems to work. By contrast the USA has a population of around 360 million, I think. If you count just illegal aliens, that is half Australia's population. I think L.A. has nearly as many people as Australia. Clearly, at least to me, it's insane to think one hoary old system is going to be useful for the common man when stretched across that size of population.
Then, too, all people are not the same and a small state that is functioning well for its inhabitants might be dissimilar to five other small states with happy populations who like different things. Variety is the spice of life. Let the spice flow.
A huge system also acts as a reflector for power, which is bad. It means a large system has more power than a small one. A large system gathers corruption, doesn't serve its population, and may misuse power.
Types of government systems that could be swapped might be, oh, a council of greybeards (vigorous elderly people promoted by their local populations to a capacity with no pay who serve a certain amount of time), democracy, minimalist government, I dunno. Each type of government would probably need its own optimum time period.
Obviously it would help if certain unwieldy problems such as energy fulfillment were solved, but I think that's on the way and also would have happened sooner without the jumbo corrupt systems fucking everything up.