People have been commenting that in the old days, adults could feel free to chastise kids who mis-behaved on the streets.

Well, it seems to me that nowadays adults don't actually use the streets much. Recently, when walking to a friends house (about 20 minutes away through a city suburb), I noticed that the only people I passed on the pavement were children and old people. All the adults go everywhere by car.

I think that a contributing factor might be that kids have gradually becoming used to behaving how they like because nobody sees them at it. If any adult did try to intervene, they would be unlikely to have the support of 'passers by' - because there wouldn't be anyone passing by.