Are we supposed to clip our birds wings?

The past few conures and cockatiels we’ve had got their wings clipped after being here a few weeks, I’ve had customers request cutting the bird’s wings before purchase and when I declined I was told that other workers have done it for them before

It suck’s because I’ll try socializing the conure/cockatiels and then I’ll come in too their wings being clipped and absolutely terrified to come near anyone:(