"Finally, his end conclusion is still spurious - if you lock up more people than everyone else clearly law enforcement isn't the problem."
Not true at all. The way to measure how lax law enforcement is is by what percent of crimes result in punishment. The U.S. has a very low clearance rate compared to other countries ( http://sowf.moi.gov.tw/stat/english/enational/j54.xls ). I don't have the stats on hand, but the conviction rate is also much lower. In many cities have about a 60% clearance rate (meaning an arrest with a warrant) and then about a 30% conviction rate for homicide (http://articles.baltimoresun.com/2010-08-30/news/bs-ed-berns... ). In other words, in only 20% of murders is the perpetrator found and convicted for murder. In Japan and Singapore, the rate is in the 90%'s (arguably this rate is suspiciously too high). The U.S. has much less effective law enforcement. Not surprisingly, Japan and Singapore have very, very few murders, so their overall incarceration rate is much lower.
When you look at other crimes it's the same deal. When you talk to people in who live in urban neighborhoods in the U.S. the default expectation is that burglaries, armed robberies, car break ins, etc, etc will not get solved.
As hard as it is to believe, even drug enforcement is quite lax in the U.S. cities. The first dozen times someone is caught on the street corner dealing drugs, they get a day in jail and they are right back out there. And most of the time the police just drive by without doing anything. Think that happens in Singapore? In Sweden? In anywhere in the developed world outside of certain urban cores? Drug policing is incredibly lax. So the problem grows, turf wars break out, fighting breaks out, the population calls for the police to do something, there is a crack down, and all the drug dealers who were suckered into thinking the police didn't care get caught up and end up in prison for a long time.
The problem is that American policing is both too lax and too harsh. The best way to prevent crime is too have predictable, high probability consequences for crime. Harsh but low probability punishment is much less effective.
The type of policing in the Wire (which matches most of what I have read in real life about the problem) is the worst possible way to prevent crime. Remember how the police wait for months and months, watching the gangs, knowing everyone who is committing crimes, without doing a thing about it? That is what I mean by incredibly lax policing. In the 1860's Philadelphia had a gang problem. A certain gang notoriously controlled an area of town and was causing the people all sort of trouble. So the police chief sent in a force billy clubs and beat the gang down. The gang problem disappeared, the gang members did not have some permanent criminal record that prevented employment, it was quick and effective action.
Notice how in the Wire and in real life the police arrest someone for drug dealing, and then are back out on the street with no consequences a few days later. The police shrug it off, as if nothing can be done about it. But why not put every person who has been arrested for drug dealing under anti-loitering probation for the rest of the year. If you're caught loitering at that same corner again, you're told once to move along. Second offence you get 10 hours of community labor, and caught again you get ten lashes with the billy club. Baltimore has no shortage of community labor to be done, lots of trash to pick up and lots to clear out. I guarantee you'll have the streets clear of street dealing in no time. Youth won't fall in the drug gang trap as much and violent turf wars over corners will cease.
And then there is that whole issue of the schools. Again, school discipline is ridiculously lax. The default punishment is sending the kid to the principal's office, the harshest punishment is suspension or expulsion. None of these are even punishments to the types of kids committing the offense! See for example: http://www.anurbanteacherseducation.com/2011/02/tfa-alumnus-... and http://www.city-journal.org/html/13_1_how_i_joined.html neither of these situations is that abnormal.
America is like the abusive parent who mostly let's the kids do whatever they want, and then everyone once in a while gets drunk and beats the kid silly. Naturally the kids grow up to be criminals. What is needed is strict, firm, predictable law enforcement.