Some basic moral assumptions
A moral standard that I cannot possibly live up to is moral standard that I am not willing to accept as true. If a moral standard implies a certain action but I cannot practically perform that action every time that it would be required, that moral standard cannot be valid. A moral standard should take into account what is practically possible. A moral standard should enable me to act carefully and appreciative in this world, not be a burden to me.
From a moral perspective, doing something willingly and doing something knowingly are the same thing. By this I mean, both intentionally poisoning a river and buying some cheaply produced products knowing that their production processes poisona a river, have to be judged equally.