I’ve potty trained birds. Literally. They would tell me they needed to go when out of their cages by doing a dance and then wait for me to hold them over the toilet so they could go.
So can not may not really be can not.
I, too, could potty-train a macaw but it was not so elaborate as this. When outside her cage, there was a designated poop perch and if she was out longer than 20 minutes, I would take her to the perch and let her drop cargo. She knew the drill. It was very effective.