Quebec had a big problem with this a while back and the organizers (the main ones, anyway) have banded together and taken a stand against "chokers" (people who call "IN" and choke out at the last minute, or just don't show up).
Problematic players find themselves placed on waiting lists until the last minute (if the game hasn't filled up) or just outright banned for a season by one or all organizers (depending on what they did and how frequently -- obviously shit genuinely does happen and we don't penalize people for it).
Some organizers have also taken to not accepting "tents."
Similar consequences are placed on people who ditch games early.
In the past two seasons we've seen almost perfect attendance rates.