In HS, double cast show of "The Outsiders" one of our Ponyboys was more interested in basketball.  He got cut, but came back to play Wimpy in "Popeye" (very appologetic, but I wouldn't've taken him back) because the other Wimpy was academically ineligible.  We had a problem with parents not liking the late timing and length of rehearsals, but they made most of them anyway (kids were in show).  One actor we had major problems with him missing rehearsals.  This was in "Something's Afoot".  Our next show was a melodrama with the Sweet Adelines.  Same actor, same problem.  I was playing a minor role, working as a dresser, running the curtain, trying to talk to the guys in the booth on a radio with dead batteries, and understudying the no-show's part.  He was there for the performances.  Fortunately he did not audition for our most recent show.  We have the small town/shallow talent pool problem.  I would really like to have everyone in our next "real" show (not the interactive one we're doing next) with a small role actually understudy a major role.  It's always easier to fill a small role than a big one at the last minute.