Do any of you who are castigating the idea of getting a pet bird have a pet dog or cat?
Does the knowledge that some parts of the dog trade are extremely cruel mean that it is wrong under all circumstances to have a pet dog? Does the knowledge that some cat owners, usually for sensible reasons, keep their pets as indoors cats make you think that owning a cat is a cruel confinement of a wild creature?
Having a pet bird is like having any other pet. You do your research to ensure that you only source the bird from someone who breeds and keeps them humanely. You check out the needs of individual pet bird species to make sure that you provide them with the living conditions that they need, which usually involves keeping more than one bird, getting the largest possible cage and making arrangements for them to have periods of free flight in the house.
Pet birds in the UK are bred in captivity, not sourced from the wild, or from wild parents, grandparents, great grandparents etc. Some species, like dogs, have been bred for so long that they no longer correlate with any species in the wild. They are adapted for life as pets, just as dogs are
Of course there will be some breeders who don't have high welfare standards. So you have to check that thoroughly, just as you do when buying a dog.
I have a rescue budgie (it flew into our garden and I couldn't trace an owner) and a pair of Bengali finches. They live together in an enormous cage. The finches in particular are very happy. They are always extremely busy at DIY, which mostly involves shredding the parsley plant I put in the cage and using it to make nests. I have a running argument with them about whether they should put it into the specially provided nesting tray or on top of all their food in the seed tray.
Personally, I would really recommend finches, because they are always so relaxed and busy. It seems to easy to give them the fulfilling environment they need. Cleverer birds, like budgies, cockatiels, parrots need lots and lots of input to help them have a full life.
Generally it is wrong to have a single budgie. I did get a companion for the bird that arrived in my garden, but it has predeceased him and I can't buy another companion without getting into an infinite budgie cycle. The finches have to be his only companions which is sad. But he is active and flourishing and I'm doing what I can.