How many times have you been told (or told someone else) that tyranny is bad and democracy is good? Sometimes, it's glaringly obvious - the "Phantom" comics have explicitly said, on multiple occasions, that the solution to all your problems is to tip the monarch out and elect your own leader. This is particularly true in the US (where, granted, they did fight a bloody war to buy the right to democracy, so there's a bit of historical bias going on here). And we do have plenty of evidence that monarchic systems can go really, horribly bad. Granted. But democracy isn't the solution - it just shifts the problems around.
First off, let's dispose of any notion of pure democracy. In a pure democracy, every collective decision is made by equal votes from all members. Basically, that means a referendum on every trivial point of government - impractical even at small levels, and utterly impossible at the level of a country. Instead, we have representative democracy, where the governed people get to pick the person or people they want in charge. And in most Western countries, we really have party politics - you're not even picking the people, so much as picking the party they belong to. (And that's before even starting to look at crazy indirections like the US electoral college system, where people act like they're voting for a president based on his/her party, but are really voting someone into the electoral college, and those people get to vote.)
So the primary form of government used and recommended in most Western countries is some form of representative democracy. People get to submit their opinion on who should be given the power, and that person (or those people) get/s to rule for a few years, before everyone gets another big shuffle-up and we start over. In theory, it keeps leaders accountable, because they get tipped out of office if they do badly. Great. It has a few problems, it has significant costs, and unfortunately it ultimately comes down to which candidate has the best publicity, but it's alright in theory. The trouble is that people are stupid and/or evil. The people who elect people are stupid and/or evil. The people who get elected are usually evil, and often stupid as well. Thinking about long-term consequences means not being stupid. Thinking about the greater good means not being evil. We have a political system that is built on top of fundamentally inappropriate units of thought.
Does that mean we're doomed? Fortunately, no. There are ways to build a good system on imperfect materials. The internet is a dangerous place, and data can easily get lost or corrupted on the way to you, yet we have TCP that gives us reliability, and HTTPS that gives us dependability. All we need is to build a system that minimizes the problems, and - most importantly - gives us a way to get around them.
And monarchies give us that.
But what about those tyrannies? How do we make sure we don't get the wrong people in power? Let's look at how the internet works. Everyone who's using the internet is a part of it; there's no fundamental difference between "rulers" and "subjects". You connect your computer to the net, and you can talk to people, and people can talk to you. There are easy ways to block some traffic from getting to you, or from leaving your computer (firewalls). At this point, what I've described is basically anarchy - nobody has power of any kind. The trouble here is that everyone has to do all the work of firewalling, even though the person next to them is doing the exact same work - and not everyone has the skill (or inclination) to manage a firewall appropriately. If the internet were purely built on this basis, every non-technical person on it would be a target, all the time.
So people club together. In my family, I'm neither the head of the household nor the owner of the house, yet I've been given the job of protecting everyone from the nasty creatures that run amuck in the environs. I have authority over our network, and I get to choose which IP addresses and ports are off limits. For me, this is a responsibility to serve; but the exact same technologies and forms of control are what create the Great Firewall of China, a prime example of tyranny. Where's the boundary between "people clubbing together" and "totalitarian government"? Ultimately, that's the key here... and it is...
... the freedom to leave. At any time, anyone in my house could get hold of his/her own internet connection, the exact same way that I got mine. (In fact, anyone with a mobile phone already has one.) So if I start blocking sites against their will, they can all just ignore me and let me lord it over nobody. The same is true of any other platform on the internet. Don't like what Facebook's doing? Move to Google+ instead. Afraid that Google Search is tracking your every move? Give Duck Duck Go a try. Annoyed that your ISP blocks all incoming traffic on ports 25 and 80? Get another ISP. There will always be consequences - most notably, the network effect, in that people on Facebook are best reached via Facebook - but when the (perceived) costs of leaving exceed the (perceived) costs of staying, you have the option to leave.
Can this be done in world politics? I believe it probably can. There are some issues to be worked out, and it would be hard to start this system now, but there are possibilities here. The first requirement would be to drop all forms of border control apart from quarantine. We're moving toward that as regards tourism (as an Australian, I can visit any Commonwealth country very easily, and other countries like the US with reasonable ease), but we'd need to remove all barriers to migration. That would also eliminate a lot of issues regarding asylum seekers; you want to come here? No problem, just come. The second requirement would be to have some actual benefits to citizenship, else nobody would bother.
The biggest issue, though, is land ownership. As was discussed in The Valley Of Fear, it doesn't matter who owns a piece of land, as it can't be carried out of the country it's a part of. One solution would be to eliminate the ownership of land as a concept, but I don't like that. In any case, this falls under the heading of "consequences of leaving"; it would make it harder, but not impossible, for a land owner to change citizenship.
But the benefits would be huge. With open borders, governments would be forced to be genuinely beneficial to their people. They'd have to demonstrate that the tax money they collect is being put to good (enough) use, that their policies are worth living under. Instead of a system of collective irresponsibility created by massive committees and frequent rotation of incumbents, you have a system of small states that are headed by the same people long-term - people who have to own their decisions. All those people who say they'll move to Canada if so-and-so becomes president of the US? Let 'em. And they can move right back again if they find that Canada just isn't the utopia they thought (or if they miss their old friends too much - the network effect again).
Power comes from one of two sources. Either you create it, or it's given to you. If you create a country, you are in charge of it; and if someone chooses to live in your country, s/he gives you that power. The system works because power is hierarchical, and all the power in this world is ultimately owned by the One who created it. He made this world, He gave us control over it, and He is the one we'll be accountable to in the end.