Everyone who has a cigarette at the football is capable of not doing so. I realise it's an addiction but the amount of time you're within the stadium confines is likely to be between 2 hours and 2 hours 30 minutes. That's hardly any time at all. Consider your summer holidays. I'd wager the vast majority of City smokers have, at some point in their life, been on an airplane. From the moment you pass through customs to the moment you exit the destination airport you are unable to smoke. This is going to be, again in the vast majority of cases, a damn sight longer than 2 and a half hours. Yet I'd also wager almost every single one of those people has managed to last that length of time without having a cigarette. Why? The answer is simple, fear of the repercussions. If you're caught smoking in the airport, or on the airplane, then you'll be hit with a hefty fine and potentially miss your flight, or be banned from future usage of the airline. The reason people smoke at the Ethihad is because they think they can get away with it. They are aware that, just like the airport, smoking is strictly forbidden, but they believe they can still do it and the punishment will either not be forthcoming, or else will be extremely light indeed. As long as the punishment is lenient, or non-existant, then you will have sizeable numbers who ignore the rules and smoke simply because they can get away with it.
As for the poster who was asking why he had been singled out for punishment when others had been left alone, I'm pretty sure it probably was because you didn't look like you'd cause trouble. You were likely chosen because it would be fairly easy for them to deal with you. And? That might not be particularly fair but since when has the "he's doing it so why am I the only one being punished?" argument actually been an acceptable one? Also, as a point of order, the policy hasn't changed, smoking has never been allowed on the spirals. The enforcement of the policy may well have changed, but certainly not the policy itself. That being the case it's also not a valid argument to claim "well, it's been tolerated for months so why punish me now?", you've known for those months that what you were doing was against the rules, just because it was previously ignored doesn't mean you weren't aware it wasn't acceptable. There is no reason why they should have warned you they were now being stricter in enforcing this, you're told at each and every game, via the tannoy, that smoking everywhere in the stadium is actually banned.