I’m guessing your students are either hearing impaired or just haven’t heard these songs before: they’re fairly obviously Spanish lyrics. Also a bit of duff German in there too!
The vast majority of people I've mentioned it to never noticed the background vocals in the Clash song, and thought Beck was singing gibberish...
But, also, most people aren't weirdos like us on the forum- they consume music more passively, and don't pay nearly as much attention to it.
Out of interest, how old are your students? I’m 46 and think of these as ubiquitous but can easily see that they aren’t for a younger group.