I'm actually against the idea of domesticating birds and putting them in cages. I have had parakeets in the past and in hindsight, I think the birds were very unhappy. Moreover, parakeets require a lot of care and even the smallest change can upset them and disturb their health. People buy parakeets not knowing much about them and think that they're very easy to care for but that's not how it is.
Temperature changes, bacteria, new foods, stress and even the quality of their drinking water can upset their digestive system and cause diarrhea among other things. Their cage also needs to be cleaned regularly, they need a clean, hygienic and comfortable environment in a warm (but not hot) temperature.
It's best to not buy and cage these animals. They are better off in their natural environments. And if we don't buy them, stores will have to stop selling them.