In my humble opinion this is the flawed assumption in the line of thought you advance. Technology isn't universally disposable, that depends on the replacability and support structure around any specific source of complexity (edit: and purchasing power)
You haven't solved much of anything with automation if the final word is "don't worry how it works, we'll come over and bill you to fix it"
Odd, because that's how almost all "automation" in everyday life works. How many people actually understand the operation of, or could fix, their dishwashers? Their cars? Even their coffee-makers? Yet dishes are washed, cars are driven and coffee is made, mostly uneventfully.
Is industrial technology different? A little, but not that much - if it doesn't work, there's someone out there who can fix it, for a cost. If communications are too difficult, you might keep them in-house and pay them a wage. If not, maybe they work for another company, and you pay them for their time. Or just buy a new machine when the old one stops working.
Why you assume that is universally true is beyond me though. How do you expect societies that are incapable of adequately maintaining roads or developing safe architecture to house their population to sprout the mentality and savoir-faire for complex operations?
For sure my argument is not universal either, but I believe you transpose properties you are familiar with to a world you are not.