> I don't know how a bird lover can keep a bird in a cage
I'm convinced that people that keep (uninjured) birds in cages are narcissistic sociopaths. This is based on the conversations that I've had with them about it. Life's too short to deal with people like that. I'm thankful for the indicator to avoid them, but I'm sad that it's at the expense of a bird.
That seems a bit harsh. I have two rescue parrots that live in large cages (indoors). I let them out every night when I get home from work, and they're given plenty of toys and material (including native blooms) to interact with every day while I'm gone.
I buy a couple of pinewood storage crates for them to play in and destroy every month. I also spend over half an hour every morning cleaning all their food and water containers, and cooking them breakfast (sweet potato, corn, fresh apple, assorted greens), I don't even make myself breakfast!