It's a multitude of causes, in my eyes.
Increased individualism, increased vulnerability, increased desire to be seen or heard, increased anxiety around self and being correct or valid, increased consumption over participation, increased distance through comments rather than community and discussion, incentives around voting pushing extremes, platitudes, emotionals, etc and inhibiting and often discouraging diverse views, founded reasoning, effort into these.
/edit: I just now deleted a comment that gave a reasoned answer to a broad question, after seeing it received down votes (which I interpret as not appreciated and deemed a negative contribution to the community). Sadge.
Contrary to other comments I don't think Lemmy overall is and better than other platforms. It differs my instance and community, but we have the same systematic issues on here.
Germany here. There are some smaller differences by state.
Some states collect biological waste separately, while others collect it as general house trash.
Packaging trash is paid for by the producers beforehand, then people collect the packaging (most often plastics, making many people think we're collecting plastics in it), depending on state, either in yellow bags or yellow trash bins. Every two weeks, people put their bags next to the street, and a collection truck goes through and collects them. The person responsible for it is often based on house rules (contracted out, or a rotating inhabitant flat list). Plastics get recycled, to some degree. Some of it goes into burning, so the burning processing plant has enough burnable material.
Paper is collected separately from house trash, too, and collected at intervals. Multi-tenant housing often has shared bins, because there's no or little cost associated to the bins.
"House trash" is collected in bins. Every two weeks collected (placed next to the street, same stuff as above). Some multi-tenant housing can have per-flat bins. Depending on their size, they cost a different fixed monthly fee. Where I live there's 24 individual bins, every one in its own labeled compartment, some with a lock. Every two weeks, everyone moves their own bin next to the street and then back the next day (or later, depending on diligence and being away). For most of Germany, the trash gets burned.
Every seller of batteries has to accept/collect used batteries. Typically, supermarkets have small boxes at the entrance or exit.
Twice a year you can put bigger stuff like furniture next to the street. Some people will go through the streets and look or take what they can use. A truck collects them as trash.
Following some plan or schedule, but not particularly regularly, there's a moving collection point for small special waste. Like eletronics, fat, chemicals, etc. For the regular people. This is especially for people who can't drive the stuff off by themselves.
You collect electronic waste and drive to a communal collection point, for free. Communal or region collection points have various types of waste they collect for free, and also some types of trash and bigger or commercial trash dumping costs money (like construction and demolition waste, soil, special kinds of waste).
Bottles and drinking cans are either single-use or multi-use. You pay a deposit and when you bring them back you get it back. All single use bottles and cans use a common system, with an image code printed on it, and every seller of them has to collect them no matter where they come from specifically. So as a consumer you can bring them to any supermarket. As a supermarket, you participate in a centralized system that shifts and receives and pays the deposit/payout money as necessary.
Human waste gets flushed away, moves through the sewers, and gets collected and processed in sewage plants.
For restaurants with fat waste, for example, there are businesses that handle the collection and adequate waste handling.
Simple glass, like glass bottles, not like windows, you collect and then bring to one of many collection containers in your neighborhood. They're separated by white, green, and brown glass. They get recycled.
Clothes you bring to collection containers somewhere in your neighborhood or district.
Man, this became a long text. It's quite the intricate system.
I can see in the shared bins how careless and space-wasteful some people are, butting full boxes in their original shape in there, while I always cut them up, taking up minimal space. I don't think shared bins for costly trash would work.
The separation of packaging materials from general house waste can be somewhat of a hassle. I wonder how feasible automated sorting would be. Switzerland does it like that. I feel like it's mostly because automated sorting was not as feasible when the system was introduced, and then it was an established system. It may also have to do with the calculation of the cost for the companies paying the packaging waste cost.
/edit: Added bolding to make the text more accessible/scan-able.