That's a really interesting and observant question! Yes, absolutely. You've actually touched on a specific and intentional design strategy used in urban planning and public space management. Trash bins with smaller openings are a real thing, and they serve exactly the purpose you guessed: to discourage people from disposing of large, improper items.
You'll often see these in city centers, parks, transit stations, and other high-traffic public areas. The logic is straightforward. A standard, wide-mouthed bin can easily become a receptacle for everything from household garbage bags to construction debris, which is costly and inefficient for municipal crews to handle. By limiting the aperture—sometimes to a narrow slot or a small circular opening—the bin effectively "enforces" its intended use for everyday, on-the-go litter like wrappers, cups, and small containers.
This design isn't just about physical restriction; it's a psychological nudge. The small opening sends a clear, non-verbal message: "This is for small trash only." It helps prevent the bin from being overwhelmed quickly by a few large items, which reduces overflow, keeps public areas cleaner for longer, and lowers maintenance costs. It's part of a broader approach called "crime prevention through environmental design" (CPTED), where the physical environment is shaped to encourage desirable behavior.
Of course, it's not a perfect solution. Critics might argue it can also discourage legitimate use if the opening is too small. Therefore, it's usually one tool among many, often paired with clear signage (e.g., "Litter Only" or "No Household Waste") and a consistent schedule of emptying. So next time you see a bin with a curiously small opening, you'll know it's a thoughtful piece of urban design, quietly working to keep the city tidy.