They have a QR code which must be scanned by the app to unlock the bike which in theory tells who unlocked it last but I suppose it depends on the phone system there among other things.
My 12 year old son and his mates have figured out how to hack the things anyway.
They're a bloody menace here, they're everywhere and people just leave them anywhere.
They've started here with the share car system now. Swipe the qr code, jump in and away you go.