I mostly agree, but I do think the police could do more to crack down on the most brazen instances of gangs being the de facto government of various neighborhoods.

It seems like a lot of criminals, start off rather young charged with crimes like shoplifting etc, and that record haunts them forever, by shutting off a lot of opportunities forever.

That's not my sense from the various ethnographies I have read. Where are you getting that from?

I found it rather surprising that such kinds of conditions exist in a developed country like the US; its usually something you find in less developed countries

There is a racial element to this. When I was traveling in Brazil, the black favellas of Brazil had a lot of similarity to the black ghettos of the U.S., and the white areas of Brazil had a lot of similarity to the white areas of the United States or of Europe.