You've just described my company, https://RECUP.de https://RECUP.de – it's working very well. Cup deposit is €1, and you can return your cup all over Germany at

You've just described my company, https://RECUP.de https://RECUP.de – it's working very well. Cup deposit is €1, and you can return your cup all over Germany at participating coffee shops and bakeries. At the moment we're at 2500 locations and growing steadily. The system is financed by a daily fee paid by the participating stores, €1 per day per location. Source: I'm one of the co-founders and CTO. :)