It suits a certain kind of person to have this obvious statistical fact portrayed as some sort of failing of existing institutions. Because it's just how statistics work it won't magically change if you're dumb enough to put them in charge but they can certainly tell gullible people like you that they've fixed it.
Reporting crimes is one of those tedious things citizens have to do to get a nice society to live in, like patiently queueing for things, or putting trash in the bin. You could choose not to do it, but don't blame anybody else if no-one does it and now your society sucks.
A few days later I got a "Caller ID blocked" call and was like "Scammers?" but I'm the kind of person who at least answers the call to say "Fuck off" if they're scammers and it wasn't a scam it was some nice lady whose job is to sift this endless pile of crime reports.
She didn't treat me with contempt, though of course she's not going to magically make the crime not have happened, or - given I wasn't sure who did it - even commit to having somebody actually do anything about it. But hey, that's statistics for you.
I disagree that somehow picking up litter is different. You're not going to magically make there not be any litter are you? No. But nevertheless in aggregate it has an effect.