This is my go to site for everything Stones, as in mlejay's question about Gimme Shelter being played on 7/26/75. Sometimes, for whatever reason, the band will drop a song from the setlist. In this case, GS was played. My guess is that the concert was recorded with 60 minute cassette tapes, 30 mins per side. It's also possible that if the taper wasn't a pro, you know, some high school kid, he could've forgtten to turn it on or flip the tape. It's happened.
"The Rolling Stones wanted to destroy hotel rooms. Roxy Music wanted to redecorate them."