These are only in areas where military operations would not and should not occur anyway. For instance, there are no border posts between France and Germany because they would likely wage war in that area which does not have posts; from Besancon north. It's just a matter of historical accuracy, since in the real WWI the Germans never considered conquering Switzerland and having a longer front with the French, instead of the direct assault they actually did. Conversely, there are no border posts on the frontiers of Russia, because they could have been attacked in any spot.
And in your case, there is a post line north of Toulon because no one save Hannibal would invade through the Alps. You are confined to the Mediterranean coast because that is realistic.
Also, they would be around Switzerland because Switzerland is obviously not meant to be invaded at all.
The line between Austria-Hungary and Germany makes a bit less sense, but it doesn't matter because under alliance the two civs' units are IZOC towards each other and they can just move units through the posts. Or maybe it was to create a historical accuracy in which the Austro-Hungarian forces would not be participating on the western front. Or perhaps they are in the area in case the two civs cancel their alliance, as this is an anything-goes situation. Their cities are so intertwined that a defined border would have to be in place to keep order, and to prevent infringements.
Regardless, this is all academic (no pun) anyhow, because the only thing you have to know about permanent fortifications is to bypass them :soldier:. Place IZOC units between the posts and send regular troops through under their guarding, attack from the sea, or simply go around the lines. The border posts should be the last things to worry about.
Are we going to use those units? 
