As best as I can tell, for anti-free-trade types, the following definition of "fair" and "unfair" are used:
"Fair" = "I like it"
"Unfair" = "I don't like it"
So it's "fair" for us to "protect jobs", but "unfair" for other countries to "undercut our wages", etc. The problem with your position is that there's no objective version of "fair".
As a result, this position leads to trade wars, as some small imagined unfairness is retaliated against, leading to reciprocal retaliation, ad infinitum. No turning the other cheek, just the all-purpose rationalization that "well, the other guy is playing fair, so I can do whatever I want".
Finally, any trade economist will tell you that it makes sense to trade even when the other side has tariffs, etc. that make trade "unfair". That analysis is longer than a discussion of Comparative Advantage, but it is proven by two hundreds years of trading history.