I was stuck in an elevator once. It only lasted a minute or two, but it was long enough for me to look up at the ceiling and estimate my chances of climbing out of there. Answer: Zero. There wasn’t even one of those convenient trapdoors. No trapdoor to open, and nothing to stand on to climb out of it. I was stuck.
My claustrophobia was just kicking into overdrive when the elevator started moving, and everything was fine.