Shelters don't do that here, as far as I know-I think Nikky may have seen a lot of declawed animals because animals that are given up are often declawed by their owners, or ran away and never made it home. My cat came from a shelter and was not declawed-she was an indoor only cat given up by her owner. They did not tell us anything about declawing , either- they microchipped her, and vaccinated her, and made sure she was spayed. That's all.
Part of their adoption info asks, "have you considered the potential for the animal to damage furniture or carpet?" before you decide to adopt an animal. If anything, I imagine people working in shelters are against the practice. Lily's info posted about her past, her personality, etc. also mentioned her scratching habits.
I definitely would never do that to her-she was 2 years old when we got her, an adult. It would be unnecessary.
(And I have found blankets draped on the corners of my new couch, and a scratching pad near by have down wonders! We've had it since February and she hasn't touched the new furniture:))