Chicago is laid out with an extensive alley system, even in the downtown parts of the city. In New York, garbage ends up on the sidewalk. In Chicago, all of that is tucked into alleys. Garbage trucks and dumpsters are all tucked behind the scenes.
That layout was done generations ago, and is probably the biggest reason that downtown Chicago smells like chocolate instead of trash.
Ex: https://www.google.com/search?q=barcelona+trash+bins+parking...
Is Bloomer's still violating EPA particulate regulations during chocolate manufacturing? I would've thought their new Japanese owners would've clamped down on that by now.
This was for safety reasons: alleys provide many poorly-lit, poorly visible locations to commit crimes: mugging, illegal transactions (drugs etc.) and worse.
So just to be clear that alleys aren't necessarily a net benefit. New York may very well have been much safer, at the price of late-night garbage out visibly for pickup.