Some of the suggestions on here are ridiculous, penalise season card holders for not attending, what the actual fuck!
The ticket exchange should be pushed harder though as it's a great way for passing the tickets on to other fans when you can't attend.
I travel down from North of Scotland and some games are impossible to attend, like WBA at the end of the season, scheduled midweek and no holidays left.
Fortunately was able to sell the tickets on the ticket exchange which was win win for me and the club!
Early leavers are by far the biggest issue, I never leave early but I left early in the Monaco home game as I was losing the plot when we got the pen given against us as I was about to have a heart attack. I was the dickhead who left early and missed a great match, I can't understand why people leave the match early every game especially when the outcome is still not decided