The chickens are (or should be) only raised for eggs they produce and not for the meat. There is a BIG difference if you raise a few chickens to have fresh eggs everyday and a bunch of them for meat. It's not really worth raising them for the meat unless you raise a lot of them and then you get into the problems of smell, noise, etc. I personally can't wait for the day I can have a few chickens in the backyard for fresh eggs but I honestly believe that there's just too many uninformed people in Calgary that will veto the idea. I've lived in cities where people kept a few chickens for eggs and if they are kept right, you never ever know that there are chickens living next door. I've lived in houses where people kept friendly chickens in the backyard and they are a delight to have around. There are some wonderful chicken breeds out there that are very quiet, make great pets and have great eggs on top of it. Generally all people ever hear of chickens is all the bad things, that they smell, are loud, carry diseases and attract vermin. I honestly believed that too until I started living and working with chickens many years ago. If this was a discussion about banning dogs (or many other animals for that matter) and you made a list of all the bad things that come with irresponsible dog owners most likely people would ban them too based on that list.
The amount of houses here that have dogs that crap everywhere, smell and bark all day don't seem to be enough of a concern. Yes you can call bylaw services but I have never personally had or heard of many successes with them solving bad dog owners. However, it only takes a few chicken growers that have no clue what they are doing to screw things royally up (but the same can be said of dog owners). In Calgary you do also have the added problem of the weather and chickens will have to be killed before winter unless you have a proper heated home for them or you take them inside. I'm not bashing dog owners, I have a dog myself and the majority of dog owners are good with their dogs.
For many people this is not about being eco-friendly or jumping on a fad, it's simply about knowing where your food comes from, what it's fed, how well it's treated and having the freshest ingredients possible. I know I'd love to have a trout pond in my backyard too for a fresh pan fry instead of buying fish shipped in from abroad grown with human garbage.