No real children in the streets

"It is startling to see actual San Francisco children in the movie — they did not seem to be hired extras." writes Tyler Cowen in Marginal REVOLUTION blog. He is comparing a 1970 movie with today's street scenes. You cannot see children on the streets of San Francisco. Neither in most European capitals. Cowen appears to take for granted that the children in today's movies (and reality?) are hired extras. For a change: a Jewish Street in London, today, from The Guardian.