That's an excellent and practical question for urban planners and facility managers. The typical lifespan can vary significantly based on climate, usage, and maintenance, but here's a general comparison from my experience.
A well-made polymer concrete trash bin typically lasts 10 to 15 years in an urban setting. Its main advantage is incredible resistance to corrosion, graffiti, and harsh chemicals. It won't rust, dent, or fade easily from UV exposure. The thick walls also dampen noise. The primary failure points are usually the metal hinges or lids if they aren't also corrosion-protected, not the concrete body itself.
A stainless steel trash can, particularly one made from high-grade 304 or 316 stainless steel, can also last 15+ years. Its strength is resistance to physical impacts and a sleek, modern look that's easier to keep looking clean. However, its lifespan is highly dependent on its environment. In coastal areas with salt spray or in places where de-icing salts are used, it can suffer from pitting and corrosion over time. Scratches and graffiti can also mar its surface if not cleaned promptly.
So, while both are durable, the choice often comes down to environment and priorities. Polymer concrete excels in harsh chemical or coastal climates with minimal maintenance. Stainless steel offers superior strength against abuse in drier, inland cities but may require more care to maintain its appearance. For the longest overall service life with the least upkeep in most conditions, polymer concrete often has a slight edge.