Starsector 0.97a is out! (02/02/24); New blog post: Simulator Enhancements (03/13/24)
Wyvern is 100% correct about the math.
Does Tech-Mining even work? I've been mining on a world with vast ruins for a few years now and have gotten nothing.
Waystations also cause your colony to stockpile supplies and fuel, plus they don't cost an industry and give an accessibility bonus. The supplies and fuel are not free but my guess is whatever industry you put in place of tech mining in addition to the accessibility bonus will make a lot more money that the value of the supplies and fuel from tech mining. I don't really see how tech mines compete with other industries right now. Even when I've built them on vast ruins, the loot has been unimpressive, but maybe I've just gotten unlucky.