I could never do that, at least not in England. Where my parents live in Ireland people do that, children also leave their bikes, sports equipment and toys outside and they don't get stolen. There's never been a burglary on that street, despite it being an affluent area. There are no chav types or foreigners/ethnics there. I'm told England was like that until the 1960s or 70s. Where I grew up, if you left your bike unattended somewhere for 15 minutes, it would probably be stolen.