Chaim,
I think you fairly describe problems in big business. As I said, I prefer working in small (professional!) business, where I have more control, but I recognize it is not always possible. When amoraim suggested “umanut” that was exactly that – a solitary professional offering his ehrliche services, relying on his advanced skills, whether a shoemaker or a doctor. I don’t know what would be equivalent to “big business” in their times – maybe working for the government, something pirkei avos suggests we should be careful about. Same applies to a large corporation – don’t expect them to care much about you.
But again, there is a large difference between doctors doing thing by the book and being in shady businesses where there is yetzer hara for genivah and such. Yes, ideally doctor should be doing it for a mitzva of saving life but it is OK to follow accepted business practices (see Igros Moshe 4:52 where he justifies taking payment from Jewish patients for more than “schar betala”). This is way more ehrliche than “heterim” that you are hinting to regarding not following dina demalchuta.
And I am really disappointed that all your lofty statements about the beauty of the way you are following seem to rely on such “heterim”. All I was suggesting that being in such business creates a possibility of succumbing to yetzer hara, and you finally clarified that it is a certainty …