That's an excellent question about a common urban challenge. Yes, many cities worldwide are now implementing trash cans with specifically designed small openings as a strategic tool to combat illegal dumping.
The logic is straightforward but effective. A standard, large-mouthed bin can easily accommodate oversized bags of household waste, construction debris, or other items that people might try to dispose of improperly in public spaces. By reducing the aperture to just large enough for typical pedestrian litter—like coffee cups, food wrappers, and small bottles—these bins physically prevent the insertion of large, unauthorized trash bags.
From my observations in cities using them, you'll typically see these specialized bins in parks, on busy downtown sidewalks, and near transit stops. They are part of a broader "crime prevention through environmental design" (CPTED) strategy. The goal isn't to inconvenience the legitimate user but to redirect the cost and burden of large-scale waste disposal back to the proper channels, like municipal curbside pickup or designated drop-off facilities.
The results are often noticeable: cleaner areas around bins, reduced maintenance costs for city workers who no longer have to haul away dumped furniture or bags, and a general improvement in the perception of public space. It's a simple, low-tech solution that addresses a high-cost problem, making our shared environments more pleasant for everyone.