Are you sure there's no law in Sweden? In Denmark, any store that sells more than a certain number of bottles has to have one of the reverse-vending machines to take them back and repay the deposit.
I assumed there was, but I googled it and there isn't. https://www.google.com/search?client=safari&rls=en&q=panta+f...
It sounds like this is mainly a question of enforcement - and the willpower in the city to back that enforcement. Here in Sweden we have no law forcing stores to take back their cans, but I don't think I've ever seen a supermarket however small without a recycle vending machine. Then again, we don't have the homeless problem SF does.