I disagree. Not as long as the white men in their barbershop have a much better chance of having jobs, wealth, security, etc., than the guys in the black barbershop. (Admittedly, the specific white guys in some certain specific barber shop may not. But white guys in general? Sure.) As long as there is a cultural power imbalance, the slurs do not carry equal sting, because the two sides do not have equal power to back the slurs up with violence and/or financial protection.
Let's take another comparison. If I'm a heterosexual walking past a gay bar late at night, and I hear someone yell out, "Breeder!" (not necessarily a likely scenario, but bear with me), how intimidated am I going to feel? Maybe somewhat, I guess. But will I really feel no less intimidated than a gay person would walking past a non-gay bar late at night and hearing someone yell out the f-word?
Or maybe you're saying the two scenarios are equivalent in a morality kind of way. In that case, I still disagree.
I say its racism in both barbershops because each group of men is expressing malice towards members of the other race
because of the others' race. The power imbalance does nothing to make the words of the black men not racist.
As for the "sting" factor, that is going to vary from person to person. You might not be terribly offended by being called a "cracker," but another white person would.
I ran headlong into this back in 1986 when I was working in Bermuda. A few months into the run of the show I was doing down there, a talk-show host did a series of interviews with a handful of members of my cast. I was one of them. The host was a young, attractive black woman, and most of the employees at the radio station were also black. While she and I were in the studio prepping for the interview, I noticed a very handsome, young white man in the booth working with the black sound engineer. They were laughing about something, but I could not hear them through the glass. I asked the host, "So who's whitey?" Immediately, the white guy's head snapped in my direction, and as our eyes met, his whole face and body sort of slumped. Then he left the booth. Even though we weren't on air yet, the microphone in the studio was on, and I didn't know it. The host told me that the guy was an intern from the college.
I was so embarrassed by what I had done that I got the guy's name & number from the host. When I got back to my hotel later, I called him to apologize. His mom answered the phone, and explained that he was not at home. She asked who I was, and I told her my name and that I was in the Follies show. She laughed and said that she had been to see the show several times with various visitors, and that she enjoyed it. But she was curious about why I was calling. I sort of half-confessed, and told her that I was in the radio station for an interview, said something I shouldn't have, and needed to apologize to her son. She took my number and said she would give him the message. I never heard back from him, nor did I see him again for the remainder of my time on the island.
My point is that I
clearly offended that young white man. And all it took was "whitey," which as negatively-charged words goes, carries only about 1 electron as far as society is concerned. But for that young man it was enough.