Then there are birds who are simply not cut out for flight, and may not have survived in the wild because they never fledged. My parents third bird is a relatively poor flyer who does not fly voluntarily. Especially after he suffered a stroke. He gets picked up round the body, taken to the edge of the kitchen (of course when nothing is cooking!) and given a toss so he has to fly the 50 or so feet in a straight line back to his cage. He gets to do that a couple times a day for exercise. He does pretty good when given the head start of being lightly tossed, but usually is very uncontrolled if he takes off by himself (like when he's scared or something). Poor old Barney can barely fly after 40 years

Kiwi is clipped because he plain has no concept of flight. He sure likes to flap his wings when he's holding onto our hand for dear life, but when we tried to flight him, he dropped like a rock and looked at us as though we had thrown him to be mean

He just never took flight, so we continue to clip him for safety outdoors so if he did ever get spooked or walk off his perch (which he does sometimes when excited) he wouldn't have the flight feathers he had no idea how to use and catch a gust of wind and end up petrified half to death 20' up a tree or something. Clipping is something that should be considered carefully by the owner after weighing all the pros and cons, and based on the individual bird.