Because there are 2 sorts of gamer card, those with only quality games, and those with any old crap to get the achievements.
I'm firmly in the former group, so you wont find King Kong, or those EA Basketball games on there. Some people though would rather have a bigger score even if it means having a gamer card clogged up with rubbish.
I believe they are called 'twats'.
But lets give Zap a pass, maybe he got it for an Xmas pressy or something.