How can one deal with the widespread presence of prohibited music everywhere, given people's unawareness of its impermissibility?

Singing is of two types: permissible and forbidden. The permissible kind is that which is without musical instruments—except the duff (tambourine)—and with good lyrics free from ostentation, immodesty, mixing of genders, forbidden gazes, and other Shar’i prohibitions. The forbidden kind is that which includes musical instruments, vulgar lyrics, mixing of genders, ostentation, or other prohibitions. The reality of transgression does not alter the Shar’i ruling; rather, it necessitates intensifying efforts in enjoining good and forbidding evil, and providing permissible alternatives such as Islamic anasheeds.