Well, some of US do.
Doesn't it strike you as just a bit odd that parents would take their baby to a restaurant and leave the child on a sidewalk, outside, while they munch salmon, brie, and rye bread?
Either leave the kid with old (enough) siblings, or with a responsible sitter AT HOME, or take your baby INTO the restaurant with you.
Crime or no crime, the sidewalk is NOT a place for infants and toddlers alone.
No, not of itself.
A toddler is probably safer on a Norwegian street than sitting with his parents inside many American restaurants.