From my vantage point in the midst of a thoroughly lower-middle-class neighborhood of TP. Hồ Chí Minh, there is very little crime. This is surprising since there is a large degree of unemployment, particularly among teens and young adults in this neighborhood. Kids are on the hẻm (lane) all day. They seem to be able to amuse themselves during the day without bothering the neighbors or getting into trouble. They do not intimidate or threaten the neighbors.
A similar neighborhood in California cities like Los Angeles or Oakland would be rife with youth gangs. Unemployed teens and young adults are very intimidating to neighbors in such areas.
What is it that keeps youth gangs out of the Vietnamese society? (I realize that there are probably adult gangs for the business of drug trafficking or similar social ills) I think the key to neighborhood peace is the cohesiveness of the "village". Since most of the neighborhood family wives and mothers stay at home (except for daily trips to the market or other amusements), there is constant supervision of young people on the streets. I have seen neighbor mothers take aside a neighbor's child when necessary for a long chat. All of this takes place on the street or door steps since much of life in Việt Nam is lived outdoors.
I may be naïve, however. I understand my isolation from Vietnamese society, including the neighborhood grapevine, because I do not speak or read Vietnamese. There may be many stories about neighborhood crime in the local press, but these stories rarely make it to the English-language press (which most often consists of articles translated from the Vietnamese press). However, the English-language version of the online Thanh Niên News, the online tribune for Vietnam's Youth Association, recently published an article headlined "Teenagers commit two-thirds of crimes in Vietnam metro". This article points out gang-crime in HCMC neighborhoods carried out by homeless or runaway children. Through separation from their families, they are no longer subject to the supervision of their neighborhoods, and they get in trouble. The key quotation from the article reinforces my point:
"'There is a high risk that the city’s 3,000 children who have run away from home will take up crime,' Dung said, concerned. In Vietnam, where administration is subdivided right up to the grassroots levels, local authorities maintain records of all events happening in their area including children leaving home."
On the whole, however, this appears to me to be very rare in comparison with western societies.