Honestly, it depends on the bench's materials, how it was built, and what your local recycling facility accepts. A well-made street bench is rarely destined to become 100% landfill waste, but it is not automatically recycled either.
Metal frames are the most recyclable part. Steel and aluminum are endlessly recyclable, and scrap metal yards will usually take them even if they have paint or minor rust. The main work is removing the seat slats or armrests first. If you can separate those materials, the metal has real scrap value and often gets melted down for new steel or aluminum products.
Wood is where things get complicated. Untreated hardwood or softwood can be reused, chipped, or composted. However, many outdoor benches use pressure-treated wood, varnish, or sealants to resist rot and insects. That treated timber is not safe to compost and is harder to recycle, so it can end up in landfill unless you have a specialist wood recycler nearby. In some cases, old planks can still be upcycled into planters, signs, or rustic furniture if they are in decent shape.
Plastic benches are a mixed story. Recycled plastic lumber and HDPE benches can often be recycled again, but not every municipal facility handles large, bulky plastic items. Fiberglass-reinforced plastic or mixed composite benches are much harder to process and may be landfilled. Before assuming a plastic bench is trash, call your local recycler or search for a specialized plastic lumber recycler.
So, is a street bench landfill waste? Not automatically. The best chance for recycling comes from design for disassembly and a little manual labor. If the bench can be taken apart into clean metal, wood, and plastic components, most of its weight can be recycled or reused. If it is one solid bonded unit, heavily contaminated, or made from an unusual composite, it may have to go to landfill. But in many towns, metal at least will almost always be recovered because it has market value.