luck ? hmhm i think light already planned that since he know that the shinigami will never let misa got arrested again that's why the shinigami said "you bastard yagami light so that was what u were planned"
lol it's like , if they were playing a honest chess game, or a honest match on who could catch the other first, L would win, but light basically won because he used the emotions of a shinigami , something l didnt have ,it's up to howyou want to perceive it, but ya those were intelligence data given by the creators ,
as ryuuk said, he was not going to interfere, he had no sides, that made it a fair match of chess, to see who could pull it off, but it ended up not being fairplay because of the emotionally attached shinigami , that was the only reason light won