I retract my statement that it's unambiguous. The article leaves the possibility that the host didn't know where the car was and revealed a lemon only by chance

I retract my statement that it's unambiguous. The article leaves the possibility that the host didn't know where the car was and revealed a lemon only by chance. In this case there's no reason to switch doors. The host has to know where the car is and always reveal a lemon.