Do they have a permit? That's all that counts for officiality. You can see here that metals are not on the list at all for the single extra collector in Žiri (codes 16/17): 
https://www.gov.si/assets/ministrstva/MOPE/Okolje/Odpadki/Podatki/Zbiralci-Odpadkov.pdf
https://www.uradni-list.si/files/RS_-2008-034-01358-OB~P007-0000.PDF