I would always be guided by an Avian vet when it comes to clipping wing feathers. I don't like seeing it but like everything there will be exceptions to the norm.
Clipping does seem much more the norm in the US than here. I lived in the States for a little while and outside of Zoos and Parks etc in the domestic setting it was usual. The usual argument being bird safety. I strongly disagree with the practice other than on clear advice from a Vet.Is it really widespread in America then?
I get the impression that in the UK it is rare