David Simon, the creator, is quite liberal but some of the other writers were more conservative-skewed. Simon himself believed that letting one viewpoint overwhelmingly dominate would destroy the point of the show, which is show hierarchies and systems in operation and how they swallow up even those who try to rail against them.

One of the more amusing (and true) things about the show, which I suppose is a more conservative angle, is that the drug-dealers and the kids working for them have to get up early, go to work on the corners and put in some serious hours to get their money. One of the kids in Season 4 seems to expect it to be a laugh and he can do what he wants because hey, it's crime, but he is soon disabused of that notion and made to work as hard as his law-abiding peers working Saturday jobs in shops or whatever.