The real reason for political borders are the same reason that government generally always does things.
- Define the tax collection boundaries.
- Define the ownership of property
People state that boarders are there to define the line of defense, but if government is drawing the line of defense, then they are declaring that they own the lands that they are defending.
If the private property rights were honored, then the owners could, or would collaborate, or contract our property protection, rather than the warning provided by Samuel.
11 “This will be the procedure of the king who will reign over you: he will take your sons and place them for himself in his chariots and among his horsemen and they will run before his chariots. 12 He will appoint for himself commanders of thousands and of fifties, and some to [e]do his plowing and to reap his harvest and to make his weapons of war and equipment for his chariots. 13 He will also take your daughters for perfumers and cooks and bakers. 14 He will take the best of your fields and your vineyards and your olive groves and give them to his servants. 15 He will take a tenth of your seed and of your vineyards and give to his officers and to his servants. 16 He will also take your male servants and your female servants and your best young men and your donkeys and [f]use them for his work. 17 He will take a tenth of your flocks, and you yourselves will become his servants. 18 Then you will cry out in that day because of your king whom you have chosen for yourselves, but the Lord will not answer you in that day.”
1 Samuel 8:11-18 NASB
So if the government is claiming ownership over the lands, they also claim ownership over the labor of the people. This is why government will claim tax rights over the people. This is theft if it wasn’t government, rather this is theft even though it is government, but government calls it tax.