Do some rock bands play pre-recorded music live while the singer sings?

I honestly think I have noticed this many times. The only thing that
seems to be live is the singer. I have noticed keyboards playing in
the music, when no keyboard is on stage... I've noticed guitar players
playing something different than what is coming through the speakers.
I'm a guitarist so I notice these things. I only seem to notice them
in large concerts though. I noticed guitarists pretending to use a
particular miked tube amp, when it obviously sounds like they are
playing through something else.

I can understand if they are doing this for performance reasons, but
I'd just like to know if my suspicions are correct.