Possibly the solution would be to have some kind of soundproofing backing material on the converse side of the drywall panels. Including this could be required by regulation which would be easier to enforce than some kind of abstract acoustic property. One of the interesting arguments that Brian Potter made is that you're usually better off trying to move the issue from construction to manufacturing.

This is basically similar to how leaded drywall is used to shield X-rays. Of course, there are additional costs associated with the hazards of lead.