Hmm, has anyone ever seen an inner city school? Now this is all coming from my personal experiences. Baltimore is real bad (watch The Wire, good show I guarantee it). I lived in Baltimore for three years and the inner city school system is pretty much a prison. Part of the reason was the demographics - poor, lower class African Americans and other minorities. The city has a terribly high crime rate and drug trafficking.
Now the school life on the other hand is terrible. Some of the black students that never graduate high school end up in the street. I'm not sure about the dropout rate but I think it was around 30% for the students. From my personal perspective, some of the black students in my class didn't give a shit about school, they acted tough because life in the street have taught them to be tough. The high school mentally of the kids were "if you're not tough, you're a pussy." With that kind of peer pressure amongst the student, it is very, very common to see a lot of fights in class. I'm sure everyone remember their high school experiences with the social cliche and groups like jocks, nerds, geeks, preps, posers etc. Well there were actual gang members and criminals in my class back then (and some student just came to school to deal drugs). For me the school wasn't a safe environment, it was prison. I think another part of the reason for this problem was that some of the students were raised by crackheads, bad parents, or parents who were busy working and never seeing their child. One of the most important institution in one's life, family, is lacking in most of the students. And you can see the effects if you visit these urban school. The violent behaviors were very common in my Baltimore school and I can somehow justify Chicago's action for school safety based upon my experiences growing in Baltimore.
But when I moved to a rural community in Kentucky, everything was so laid back, the school environment was small, local, and very friendly. I really love the country side as compared to the inner city. Now installing 4500+ cameras in my current school would be senseless. :]