From a game-theory POV, all wars are caused by misunderstandings / partial information. If each side really knew the true strength of the other side, it would be clear which would win and therefore actual war is illogical and unnecessary.
There are also genuine uncertainties about the future: things that neither side knows but will impact the outcome. Because of that, there is always a range of outcomes for a conflict, and so both sides would still have an incentive to carry out the war.
Consider, for instance, if there are two countries (A and B) looking at conflict with perfect information. Given their relative strengths, the war will cost both $1 billion, but A will win and reap $1 billion + $1 in plunder. In your model, B will always surrender and give A $1, but the reality is there is a big spread about both the costs and the gains. Lots depends on how well each side fights and responds, even with perfect knowledge of the other.
So...you know, if it's the US versus...the Philippines[1], then sure, the uncertain range of outcomes is small enough that rational thing for the Philippines to do is surrender. But for countries that are even reasonably well-matched, they would want to fight with the goal of making the conflict unattractive for the other side. Probably the best historical example of this is the USSR in Afghanistan.
[1] I am sure the US would never invade and occupy them just because the US found it convenient ;)