I wish I was better about paying attention to channel names because I did watch a video a while back and this was basically the whole video summed up. Like, everyone knows Light was an arrogant fool who sewed the seeds of his own destruction but his solution to the societal problems he lamented about in the first chapter was literally something only the juvenile son of a cop could have come up with.
To Light, Crime was the source of society's "Rot." And his philosophy on what constituted "crime" was basically about normal-ass people who were willing to break the law. you know, the laws Cops enforce.
It also explains why he's indiscriminate rather than surgical. Because of his own biases, he never stops to consider the flaws in the methods of who gets arrested, or how that never actually seems to have an impact on Crime Rates tm. Cops (like Light) simply see this as evidence that they're not arresting enough people! That they're not going far enough! And these are the values our protagonist was raised with. A surgical strike would let Real Criminals off the hook, while targeting people who, yes, may be more evil by orders of magnitude, but they do it in a LEGAL way!
I don't think the story ever consciously addresses this. The Watsonian explanation for that would be that we don't really get to see exactly WHAT values Light's dad instills in his children - he's a major character, but Light spends far more time putting him on a pedestal than actually engaging with him. A couple Doylist explanations might be either that Ohba didn't condone Light's actions, and considered an outside exploration of his motivations to be either uninteresting to explore, or perhaps too much of a challenge to pull off in a story that so heavily revolves around the protagonist's inner monologue. I think it's far more likely, though, that this wasn't intentional - Light's dad was a cop so that he could be on the Kira taskforce and we could get the drama of Light being hunted by his own father, and the blind spots that created for both characters. Knowing the story, and how these characters are used, I find it hard to believe there were intentional ramifications beyond that. But that doesn't change the fact that they're there, and more than anything it serves as an explanation for why Light was the way he was.
