Legal Question in Criminal Law in Michigan

It's called ... "car theft"? Keys being in a car is not a defense ("Oh, it was too much of a temptation, ladies and gentleman of the jury! The owner should have known better that no one could resist opening the car door, sitting down, turning the key and driving off in that 1978 AMC Gremlin! My client is just flesh and blood!") And it's also not "entrapment" -- which might be the word you were searching for -- because (1) You don't say that law enforcement set this scene up [entrapment must be impermissible Government action], and (2) merely presenting an opportunity for someone to commit a crime is not entrapment in Michigan: law enforcement would have to engage in reprehensible conduct that induced an otherwise law-abiding citizen to commit a crime under similar circumstances. Even if police had left an unlocked car w/ keys in it in a parking space, that wouldn't fit Michigan's entrapment test.