We play our own version for two main reasons (there are often others...). Firstly, we may not (in fact probably don't have...) the instruments of the original. Example: our singer does a vocal impression of the trombone solo in Beds Are Burning. We once had a few mates on stage with us as a horn section, and it was glorious, but without them, it's 'Parp Parp' from the singer. Secondly, I play drums. I'm (modestly...) quite good, but not up to Soundgarden standards, so I simplify the fills when necessary. RATM I can handle, or Muse, but SOAD has some pretty technical stuff going on, for which there's not enough years left in me to learn. I do what I can with 'em (and it's not catastrophic, just simplified...). Sometimes we just do it differently because we like it better our way, of course. No, it's not laziness.