"Never" is too harsh of a word. But I share in your frustration about their glossing over the reality of engineering these "simple" processes that they envision. Just the amount of engineering work to *design* with enough precision to actually build a fully self-sustaining industrial base designed to work on Mars with the individual components being small enough to plausibly launch would cost in hundreds of billions to trillions of dollars Everything in industry has unimaginably massively long dependency chains that interconnect with each other, using raw materials sourced from a massive variety of different types of geological formations the planet over. You basically have to reengineer all industry on Earth for the martian envirionment in a gigantic mass-minimization optimization problem. You can't just plop down a 3d printer and some generic "mining robot" that roams around your habitat like people envision in their sci-fi fantasies. Reality isn't so friendly.
Even worse, if you start launching stuff without doing all of that engineering work, you end up heading down a dead end. Let's say you make some smelter that takes limonite as its iron feedstock. But then as you start expanding your industrial base, you discover that you actually need a lot of sulfuric acid, and your iron production process should instead be designed to work around iron sulfate feedstocks with sulfuric acid produced as the much-needed byproduct, with a different type of smelter required. Well, guess what? That smelter that you spend $20 billion dollars engineering, building, and shipping to Mars is now scrap. It applies to almost everything. You made a pipeline out of polyethylene? Whoops, now you discover that you sometimes need to ship corrosive liquids and it really should have been made out of teflon, tough luck! Built some big piece of industrial equipment that relies on high-temperature inconel alloys? Whoops, you discover that you can't find a practical niobium deposit within driving distances, you have to reengineer your hardware for very different matierial properties or operating environments! Everything down to the tolerances on your bolts or the type of plastic you put on your greenhouses can be a costly screwup if you don't design your whole industrial layout in advance on a standardized set of hardware and know precisely what mineral deposits are where and how to get at them.
To all of the sci-fi buffs: It's not time to try to colonize Mars. It's time to learn about Mars, and to engineer here on Earth. And it's going to be in that phase for a long, long time. Want to go to Mars and hop around for a bit with a rock hammer like they did on the moon? Fine. But don't call it a colony.