That's a great question I get asked a lot by folks managing public spaces. When it comes to durability, plastic and metal urban trash cans have very different strengths and weaknesses.
In terms of pure impact resistance, heavy-duty plastic bins, especially those made from polyethylene, often have an edge. They can take a knock or being bumped without denting permanently. They're also champions against rust and corrosion, which is a huge plus in coastal areas or places that use salt on roads in winter. You won't see them peeling or developing sharp, rusty edges.
Metal trash cans, typically galvanized steel or aluminum, feel incredibly sturdy and are less likely to warp in extreme heat. They are generally more resistant to vandalism like scratching and are much harder to set on fire. However, their main weakness is corrosion. Even galvanized steel will eventually rust if the coating is scratched and exposed to moisture. Dents are also permanent.
For long-term durability, the environment is key. In wet, salty, or chemically harsh environments, plastic often outlasts metal. In very hot climates or high-vandalism areas, metal might hold up better structurally. Modern plastics are UV-stabilized to prevent brittleness, but cheap plastic bins can become fragile over years in the sun. It's really about choosing the right material for your specific urban challenges. Many cities use a mix, placing plastic in parks and pedestrian areas and heavier-duty metal in high-traffic downtown locations.