Ok, so I recently terraformed Luna.
It now has 22k infrastructure on planet it'll never need.
Between it and Earth, I'm making 3k infrastructure in trade goods.
I see no reason why I should pay civs to ship 22k infrastructure to Mars, when I can tax them to ship 3k/year instead.
So, Luna has 22k infra that's pretty much wasted.
Why shouldn't I be able to just recycle the infrastructure into raw materials? Sure it's only Duranium, but resources are resources.
Or even better, turn them into maintenance supplies for ships for a small cost of Uridium/Gallacite instead of Dur/Ur/Gal.
I don´t know what Steve would think about that, but _my_ answer to that would be: Because this infrastructure was made by the civ-economy and recycling it would basically generate Duranium out of thin air.
Now, Steve could implement something that keeps track of what infrastructure is made by civs and what by your industry and allow you to recycle _your_ infrastructure, but not the one made by the civilian economy, but I guess, that is not exactly what you are asking for.
A (in my opinion) better solution would be to implement a mechanic that makes civilian economy to use resources, but then, you don´t have any control about that and I can already hear the frustrated screams when the civs use your carfully stockpiled Duranium reserves
Perhaps make it so, that you have to hand over TN minerals to the civ economy, similar to subsidizing shipping lines, or let Aurora keep track of the amount of minerals generated by civ mining colonies, that you don´t take the minerals from?
"So, you want the civilian factories to build infrastructure for you? Well, you better hand over a couple thousand tons of Duranium to them, if you wanna get that stuff in your lifetime."
