How is selection pressure applied to a particular population by humans fundamentally different than any other selection pressure?
What do you mean by selection pressure? The quote of mine you presented was made in reply to the claim that the man-made genetic mutations of goldfish were somehow supporting evidence for evolution. Are you implying the man-made selection pressure is the same as selection pressure by happenstance? Please clarify your statement.
The goldfish example is an example of genetics, not evolution (if man - intellegence - is involved, it is not evolution)