Another fix would be to independently measure noise isolation and report that, so renters can actually make decisions based on it, and builders would have an incentive to include it, since they could more reliably charge more for it.
Someone should do that with good branding. Sorta like carfax. Call the Zillow Report or find a similar firm. License the standards and a saas interface to Inspectors to have another revenue stream (or maybe more broadly to contractors). Then it could become a defacto standard, especially if you get in with real estate agents.
