Ok. I understand. This does of course make it a lot harder. But carrier preparations are essential. I think I should stress it more in the future. It's not just fun and games for taking them outside, most parrots will need to be taken to a vet or groomer in their lifetime. So denying them the practice and throwing them straight into a carrier and major trauma isn't right. I end up taking it for granted that parrots just go into the carrier cause I have been traveling with mine since I got them. This is obviously the best way cause it's just a part of their lifestyle and they don't question it.
Yet, if your bird is tame, you should still be able to get it to go in the carrier if not willingly, at least without fear. It shouldn't be so bad that it is flapping around and getting hurt. That is as abusive as employing flooding. Basically it is flooding. Flooding with the carrier.
BTW, don't think that leaving something in sight of the parrot all its life makes it feel ok going into it or touching it. In fact it works the other way. Stuff that parrots are used to seeing only but never touching they seem most phobic of when you change it on them. They get used to being on the outside of the carrier so they can't imagine being in it, etc.
You can and should use systematic desensitization as I described above. Here's another article I did about taming my parrots to their Kings Cage when I just got it:
http://trainedparrot.com/Travel_CageIt's not just you. I get this a lot. Where people decide to ask for advice the day before going to the vet or on a trip about how to get their parrot in the carrier. Clearly it's not enough time at that point, especially for a 10 year old parrot that has never been in a carrier. This is a long term skill that must be developed. Teaching wave and turn around are cute but this is a place where training is absolutely mandatory (unless they don't care and just go in). The amount of stress you cause in the short term does come back to you because you put the parrot in there in the first place. This is why I always recommend practicing toweling, grabbing, handling, carrier, harness, etc throughout the year so when it becomes necessary, the bad experience is the exception and not the rule. On the other hand, for a parrot that never goes in a carrier but then does when it has to got to the vet only has bad things to remember it by!
With a phobic rehomed parrot it's even more important to take these steps slowly in the long term rather than all at once. Do your best to make the vet visit less stressful but when you're done with it, let's chat about how to reconcile and make this tolerable for the parrot in the long run.