That's a great question, and one that city planners and facility managers think about a lot. When it comes to longevity in an urban setting, metal trash cans generally have a significant edge over plastic ones, but it's not a simple win across the board.
The biggest advantage of metal cans, typically made from galvanized steel or aluminum, is their structural integrity. They are much more resistant to impacts, vandalism, and the wear and tear of heavy use. A determined kick or a knocked-over bike might dent a metal can, but it's less likely to crack or shatter like plastic can in freezing temperatures. They are also heavier, making them harder to tip over or steal.
Plastic bins, often made from polyethylene, have their own strengths. They won't rust, which is a key point if you're in a coastal area with salty air. They're also lighter, cheaper to purchase initially, and come in various colors without needing paint. However, their main downfall for longevity is their vulnerability to UV rays from the sun, which makes them brittle over time, and to extreme temperatures. A plastic bin can become fragile in winter and may warp or soften in intense summer heat.
In terms of pure lifespan, a well-made galvanized steel trash can in a typical city environment can easily last 10-15 years or more with minimal maintenance (like repainting). A standard commercial plastic bin, under the same conditions, might show significant degradation, fading, and cracking in 5-8 years.
So, while the higher upfront cost of metal is a factor, its superior durability and longer service life often make it the more cost-effective and sustainable choice for long-term urban use, especially in high-traffic or harsh weather areas. Plastic serves well for lower-budget projects or in more controlled, sheltered environments.