Aren't they what they call "schlüsselkinder" ?
Kids that carry with the keys to the house so they can go home when they parents aren't there.
IMHO it isn't something to be proud of.
To be truly independant, experience is required, something that kids don't have. By letting kids do as they please, they will find someone else to fill their parents' role a model. It can be your friendly neighbor's kid but it can also be the local drug dealer, with a higher chance of being the drug dealer because he will have plenty of cool stuff that the other don't have.
Well if there are only helpful people and no drug dealers, kids like this will probably grow up to become respectable people. It is probably the case where the pictures were taken but not every place is like this.