Birds are often purchased as family pets, and many birds are quite gregarious and friendly with a variety of people. But quite often, birds become closely bonded to individuals and will not tolerate handling by anyone but their chosen person. In fact, many times this turns out to be someone in the family other than the person who wanted the bird as a pet in the first place. Flock birds tend to be more social, whereas birds who spend little or no time in flocks in the wild will be less likely to get along with more than one person. I've spent hundreds of dollars on veterinary bills.
Avian medicine is very specialized.
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.