The intention of these child-shaped bollards is to act as a warning device, an informal road sign.
It's a temporary benefit though, the majority of people will get used to them and after that desensitisation usual behaviour returns, only now they may be less aware of real children at the side of the road as they dismiss similar looking things as bollards and unlikely to run out into the road unexpectedly.
Fixed speed cameras don't deter speeding everywhere, they deter speeding past the fixed speed cameras. Regular drivers on a route know where they are and slow down to within the limit to pass them.
For something like this to work they need to be moved around regularly (akin to the concept of the mobile speed trap).