As a GM, I would kill a PC in a heart beat under failure to attend games regularly. In fact, I just enforced it at my last game. The player was usually good at communicating things, but he had a string of behavior that told me he was loosing interest and didn't know how to break things off. He'd miss a game, then ask me to reschedule a game and then miss that game, etc. He missed this last game that I killed his PC in. I'd told him, and the rest of the group, the importance of showing up, but when he called me last minute and said he couldn't show up cause he had a bad hangover and was going to bail again, I just said "I understand, you wanted to drink and have a good time after a long week...But your attendance lately has put me in an awkward spot because I have to make excuses for you bailing on the game and either cancelling last minute or reorganizing other people's schedule. If you don't think you can attend consistently, say so. I'll off your character, and when you can attend I'll work in an NPC for you to play." He said fine, and I found an opening later that night for his dramatic death scene.

I try to provide incentive to my players to attend, and I go well out of my way to accommodate these incentives to provide a more collaborative story. But, in the same vein, I provide harsh punishments for rude players. As a GM, I'm not just another player. I'm required to have a lot of skills and investment in the game that the players just don't employ on the same level. I have to be a good writer, an exceptional planner that can handle the odd flexibility of a collaborative narration, and I have to be a good public speaker (so much so that I can make things immersive for everyone which is a skill itself of being able to read your players). On top of all that, I have to host the game, provide refreshments, plan food and edibles -- I'm literally planning a party for 6 or 7 people every other week. Stack that on top of coordinating schedules for the game for 6 or 7 active adults with families and careers and their own concerns consistently, and you quickly realize that DMing is a lot of work. To bail out on a game -- especially last minute -- is to throw a good portion of my past two weeks in my face, telling me you poorly planned and didn't prioritize the game.

I'm a bit more personally forgiving if it were just me feeling the burn of players not showing up. With the age I'm at, I expect at least one or two people to not show up to a game. We're in our late 20s, some of us have kids or families to tend to, others have their parents to take care of, or their jobs, or homes, or school. After 24ish, organizing games becomes a nightmare. It is literally the hardest part of my current game. I enjoy no more than 5 player parties, but I usually run a game of 6 to 8 players just because the frequency at which adult lives get in the way. I have to plan a sideboard of players. But therein lies where I'm not forgiving -- poor attendance is ruining the fun of the 6 or so other people who are relying on your attendance, who carved out a huge chunk of time from their busy life to have a few ounces of fun. And if a player cancels and I subsequently don't have enough players attending, then I have to pull the trigger and cancel it for the group. I get stuck with having to answer to my players for one players behavior, I'm the one that has to disappoint them and tell them the game is cancelled. It's just not cool at this age (my group is between 27 and 32) to do that to friends.