Why do we have fractured space agencies?

This would require the USA, EU, China, Japan and Russia to all agree on what to do- good luck with that!

Different countries have different priorities and ideals, so it's hard to get them to cooperate. Many are not exactly on speaking terms either.

That said, a lot of space projects are multinational efforts.

Shortly after the Soviets launched Sputnik, Nikita Kruschev and Eisenhower had independent proposals given to them for the formation of a global space command. Both dismissed the proposals for similar reasons. Both wanted to develop satellite surveillance programs to spy on the other nation, and were attracted to the idea of putting offensive nuclear weapons in orbit over their enemy. Kruschev was also worried that the industrial might of America would lead to our dominance of the space programs, a view that was reluctantly reinforced by Sergei Korolev. So both nations decided to keep their work separate.

That was a big mistake. The Soviets could have saved several American lives if they had told us about some of their more spectacular failures. Also, Russian engineers were often more brilliant. Imagine what Korolev could have done with American industrial production, instead of being force to work with rocket components built by refrigerator manufacturers.

Most engineers and scientists involved in space technology these days would support the unification of all space programs. It's the diplomats and leaders who keep things separate. There are financial concerns (not every space faring nation can contribute as much as the others), but the biggest reason is the desire to keep our technological developments to ourselves. Also a very small fraction of space people buy into the capitalist misconception that competition between organizations will make them all perform better.

Unfortunately space exploration is still viewed in much of the same way as the Olympics with country rivalry. The biggest problem being that it isn't even remotely cared about in the public eye. Many people forget that just because the rest of the solar system (so they say) isn't habitable that that's all there is. When in reality we came from that and it is our duty to press forward. Neil degrasse tyson expands on this subject and it's importance addressing the senate science committee seen here http://youtu.be/rmKlA_UnX8c

You need to look at history and the questions offered here as to whether Russia will cut off Soyuz access to the ISS for Americans because of Russia's invasion of the Crimea and Ukraine's desired connection with NATO - it's called war.

There is the International Space Station, although I wish countries would share more, so that Russia wouldn't be the only one making Soyuz capsules.