Amsterdam has an enormous number of bikes, but not the 9 million that Katie Melua claims (though there might be 9 million bicycles in the Randstad, the megalopolis that Amsterdam is part of), and it has some spectacular bike parking facilities, but it doesn’t have free public bikes, exactly because nobody would return them.
Most famously, in the 1960s there was a proposal for het “Witte Fietsenplan” (Witte fietsenplan — Hart Amsterdammuseum). Rental bikes do exist of course, and there have been plenty of proposals for public bike systems with some sort of deposit, but I don’t know if those every got anywhere. I never see them anywhere.
