Why can’t I take other resources?

[King Darrius]

I can take food, gold and oil, but I’m using much time developing capacitors and other munitions, why can’t I take this from those I beat, if missiles are intact then why can’t I have single use SAMS or even the minerals for making munitions, even destroyed hardware has salvageable parts and you could apply a unit for this exact reason, to take valuable war materials.