That's a great question! As someone who's observed and maintained public spaces, I've seen firsthand how these finishes age. The short answer is: it holds up surprisingly well, but not perfectly, and its longevity depends heavily on a few key factors.
Initially, that smooth, glossy enamel coating is fantastic. It creates a hard, non-porous barrier that resists graffiti (paint is easier to wipe off), repels moisture, and withstands frequent cleaning with harsh chemicals. For the first few years in a mild climate, a quality enamel-finished bin can look almost new with basic maintenance.
However, time and the urban environment are relentless. The biggest enemies are physical impact and constant temperature fluctuations. Dents from trucks or heavy debris create hairline cracks in the enamel. Once the underlying steel is exposed, moisture seeps in, leading to rust bubbles under the surface. You'll often see this around the base or on the lid's edges first. In coastal areas, salt air accelerates this corrosion dramatically.
Sun exposure is another factor. While good enamel is UV-resistant, prolonged exposure can eventually cause fading or a slight chalkiness on the most exposed sides, turning a vibrant green into a muted, weathered hue.
So, how does it compare? Modern powder coating is often more flexible and may resist chipping better, but a high-quality, thick enamel finish can be superior for chemical and abrasion resistance. Most municipal durability reports I've seen suggest a well-applied enamel finish on a galvanized steel can should last 5-10 years before requiring significant touch-up or refinishing, which is a solid lifespan for such a hard-working piece of street furniture.
In the end, while it won't stay pristine forever, a good enamel finish offers a great balance of durability, cleanability, and cost-effectiveness for cities, gracefully weathering into that familiar, slightly speckled "public works" patina we all recognize.