> they only take cans sold at the store you bought them from
That might be the biggest issue. Around here (Finland) the deposit system is universal; most beverage containers are standardized and in the system by default. And the machines accept containers not within the system, they just won't give you money for them, so you don't have to worry accidentally mixing containers with deposit and those without.
That might be the biggest issue. Around here (Finland) the deposit system is universal; most beverage containers are standardized and in the system by default. And the machines accept containers not within the system, they just won't give you money for them, so you don't have to worry accidentally mixing containers with deposit and those without.