Region specific releases on PSN bug me so much. Doesn't it defeat the point of something being like...global?
It has to do with licensing. Most companies didn't really have a European office when PS1 was the big thing so they licensed their games out to other companies for distribution in the EU. Since Australia and New Zeland also use PAL they got the scraps of the EU releases with the same strings attached.
Because of these licensing issues it becomes harder to put games on the EU PSN because more than one company owns the right to sell the game and they can't decide who's supposed to get the lion's share, and in some cases the other company no longer exists so it's uncertain how to re-aquire the rights for distribution.
Capcom in particular was very bad at getting their own games out in Europe so that's the reason it took forever to get Resident Evil and we still don't have any other than the first. Complicated issue made simple: some companies simply don't own the rights to their own games.