That's actually a really thoughtful question that many cities are grappling with right now. The short answer is yes, the openings on public trash bins can definitely be made smaller, and many municipalities are experimenting with this very solution. The logic is straightforward: a smaller opening physically prevents people from tossing in oversized bags, household junk, or even small pieces of furniture that don't belong there.
However, it's not a perfect fix and comes with some trade-offs. While it discourages large, improper items, it can also make it harder for legitimate users to dispose of normal-sized waste without spilling. Think about trying to throw away a medium-sized food container or a child's toy. There's also the concern that if the opening is too restrictive, people might just leave bags of trash on top of or next to the bin, creating a bigger mess.
A more effective approach often involves a combination of strategies. This includes using bins with appropriately sized openings—large enough for common litter but too small for a microwave—paired with clear, multilingual signage showing what is and isn't acceptable. The ultimate goal is to guide behavior through smart design, making the right choice (proper disposal) the easiest one, without causing undue frustration for everyday public use.