There are few avian experts around. Tests, procedures, and treatments tend to be expensive. In addition, birds tend to exhibit symptoms only at the point where they are fairly if not acutely ill, and treatment at that point is often of an emergency nature and therefore more costly. I'm getting married. The baby sitter is allergic.
Birds live a long time.
Budgies or parakeets can live well into their teens and among the larger parrots, ages of eighty years or more are well documented. However, the statistics may be misleading. Most birds succumb to illness or accidental death long before nature runs its course. Still, it's important to remember that your bird may outlive you or your current lifestyle. In fact, many birds will outlive more than one owner.