Working in "the ghetto"

I was most struck by the Moskos article’s discussion of the role of police in communities, and the way that different races perceive that.  It makes sense that cops are quickly disillusioned when working in “the ghetto”, and want to get out as quickly as possible.  However, that strongly contrasts with the initial view of whites, who generally seem to be excited about the power that the job gives  them and the desire to fight crime (65).  This high moral and excitement quickly decreases and almost all police officers try to transfer out of the high-crime areas (74).  I also found it interesting that black police officers were more oriented toward peacekeeping (79), as well as approaching their job as simply that, a job, rather than viewing it as their self-identity (58).  For black police, it makes more sense that they would want to transfer out of “the ghetto” because they often do not have the valiant, “crime fighting” (58) mentality  that many white officers do.  My question is: what causes this different view of the role of police, and does it affect the way that officers of different races police different communities?