There are ways of doing this without entrapment. If they want to catch bike and scooter thieves they can stake out the bike racks. I suspect no sane person leaves their bike unlocked there so they have to contrive an artificial situation to entice someone to commit a crime. How is this valuable policing? Had the police not bought a scooter and left it unlocked no crime would've been committed.
I have no illusions that the young fellow in question is an upstanding citizen but how is public interest served here? One kid gets a fine and arguably may hesitate before doing the same thing again but the problem is not this one kid, it is systemic and were it not for this news article no-one would even know about it meaning it is useless even for deterrence.
It is a waste of everyone's time, drags a kid who likely already has a shit life through the courts further alienating him, and did not even protect the property of a real person.