They do not require consumers to pay advance deposit but will still reward the consumers by giving them discount coupons for grocery or some countries will even give cash in return.
Such practice does not need two, but in fact three hands to clap to make it work; Businesses/companies, consumers and the govt. The machine is not cheap, requires maintenance and a question on who should pay for this machine/technology will also suffice. :)
My two cents worth.
I do not know where you take your above information from, but it seems slightly confused. Every of the above mentioned countries requires the consumer to pay a "x" amount beforehand (with exceptions in the US).
A deposit refund scheme means that the consumer has to pay a deposit for the beverage container upon purchase, which he will get back once the container is returned. In Germany this is legally binging (25 cents). In Denmark ist is legally binging (b/w 14 - 40 cents), in Sweden it is legally binding (0,11 - 0,22 cent) in the USA there are 10 states with such a system.
Now from a non-deposit perspective (coupons for grocieries) I agree that there has to be a cooperation between consumer and business, but the government has nothing to do with these incentive schemes since this is a business model.
I would be interested to hear more about your research project! If you need any further information on this you can contact me. Our company produces the reverse vending machines with a market share of 80% globally also specialising on the topic of deposit refund!