Ambiguous Lead Exposure in USB Audio Interface
Lead solder has two main advantages over lead free solder:


It flows at a lower temperature which causes less stress for the electronic parts and the pcb due to a decrease in thermal expansion in comparison with lead free solder
Lead seems to mitigate the formation of tin whiskers; a crystalline growth that can cause short circuits in your design


The biggest disadvantage of lead solder is that it's bad for the health of a lot of organisms. Preventing products from using lead also prevents it from ending up in land fills which causes less exposure in general.

Whether it's safe to assume that the product is only using lead solder can probably not be answered from that picture alone.