I consider myself to be the kind of person who can quite easily imagine myself in someone else's place. I don't know if I'm actually any better at it than the average person, but judging by the comment sections on social media and the conversations I've had with other people, I really struggle to get angry at strangers like many others do, even for things that anger is an appropriate reaction to.
This doesn't necessarily mean that I don't condemn their behavior, but that it doesn't provoke a particularly negative emotional reaction from me. I observe the world from a distance, and when I see someone acting differently, I generally can come up with a charitable story about why they act that way. While it doesn't usually justify the behavior, it at least helps me imagine why they're like that and reminds me that if I were in their shoes, I'd likely do the same thing.
This applies to cheating, violence, racism... Name a bad behavior, and I can come up with a story about what a person might be telling themselves to justify it. However, littering is something I simply cannot comprehend. I cannot wrap my mind around what a person is thinking when they're throwing trash on the ground for someone else to pick up. If it's something "minor" like a cigarette butt, then okay, I can somewhat understand, but tossing your McDonald's takeout bag onto the side of the road is completely psychopathic behavior to me. I don't think even the worst people in the world think of themselves as "bad" because they rationalize their behavior somehow. But if you throw trash into nature, you must know you're being a massive jerk.
Tl;dr: I want to hear the best justification for littering.
There's no justification, it's part of a broken culture.
As a Czech citizen living in a city, I see it happening all around me. By far not for everyone, but for a lot of people treating trash properly is considered a fool's errand, virtual signalling, try-hard, you name it. This toxicity is unfortunately too common in the culture, and lot of people (including me) are just afraid or tired of being seen as a try-hard. It's especially "awkward" to clean up.
Obvious littering is one thing but I recon most of the trash floating around is due to "practical littering", where people, if trash cans are full, will just "neatly" place their beloved trash next to the can, kiss it goodbye and walk around as if wind does not exist. I'm probably too cynical but sometimes I imagine the same people going judgemental when they see trash caught up in bushes.
As for cigarette butts, that's just dumb. I don't think I've seen someone toss something like a plastic bottle or a bag on the ground, just like that, more than 5 times in my life, but with cigarette butts I see them all the time -- most often just before they jump on a tram or a bus. (I'm strongly against violence and bullying, but rationality aside, to be honest, there's a part of me that is wishing they had to pick it up and chew it.)
(Goddamn, about 2 weeks ago, someone must have left some balls of yarn outside, next to a trashcan, on straight street. I was walking to grocery shop and some kind of thread was unrolled along the pavement for, i kid you not, like 150m. It was bizarre. Could have been some serious TikTok/YTShorts material if someone wanted to make a "goody PSA".)