To me karma logically makes sense because doing bad things makes the world a worse place and therefore the world is more likely to treat you bad in return. "Luck" suggests an outcome is pre-determined to be in your favor, and that just scientifically doesnt make sense. Luck is just confirmation bias.
I’ve always taken luck to be descriptive, not prescriptive. Like, it totally makes sense to say you got lucky or you need good luck today or something, you’re just describing the way things went or you would like them to go. I don’t think it’s debatable whether most people have been lucky in certain situations before. Luck as like, a thing you can have permanently, I’d say no, but I feel like that isn’t the main meaning.
Luck is more like "positive coincidence" or a "favorable chance event" but not a thing that can be actively improved or gained. Karma is believed to be moral causality. But what is good/bad differs between individuals/cultures. The universe just exists and things just happen. People decide on morality, not the universe. So the idea that good things always happen to good people isn't scientifically founded, just confirmation bias.
But unlike luck, karma can be controlled. Actively doing good or bad things increases the likeliness of good or bad things happening to you. No amount of gambling will make you luckier (statistically you would trend to be unluckier/more avergae over repetition), but for karma if you do a bunch of bad things and make your environment bad, those bad things that will happen to you in return are an indirect result of your actions.