In an ideal world, we could pair every trash can with a recycling bin (or bins), and implement an entirely new collection infrastructure designed especially for recycling. Unfortunately, most communities do not have the money for such a major overhaul all at once, so establishing public space recycling usually requires transition.
Recycling collection infrastructure is a long chain, and includes bins, collection vehicles, holding containers, more collection and transportation, a processing facility and an end market for the material. Some trash collection systems are easier to adapt to collect recycling and get the material into the recycling system than others. Highly automated systems designed to handle large amounts of trash (material we don’t care about) are not ideally suited to handle recycling, which needs to be handled more carefully to really get recycled. While making changes to infrastructure up front may cost more, the recyclables are treated like trash, more adjustments must be made to address contamination and getting the material actually recycled.
Additionally, a system based on high volumes will be inefficient when applied to public space recycling, which will not produce high volumes of recyclables right away. It takes time to build a public space recycling program, and to transition from wasting to recycling.