There was a similar topic recently for a “vending” machine accepting deposit bottle return here:
Reverse recycling aka bottle_return: Please merge with prior topic not found again
I am sure there will be more of these return machines in future so we should think about a reasonable tagging scheme for all kinds of those.
As the main purpose is not selling anything but returning different types of containers for recycling, I would favour a “recycling” key instead of “vending_machine”. Other opinions?