Absolutely true. And generally reasonable for private dwellings and vehicles. But as you move into buildings and vessels where the public/customer does not have control over their safety, this does not always make sense. Nor is it universal. There was a fire in an older office building in Chicago in 2003 that resulted in 6 deaths that could have been prevented by a sprinkler system. The city council then passed a law requiring older buildings to update their fire systems. The older office building I'm sitting in right now added a sprinkler system. My 54 story condo building avoided the huge cost of retrofitting a full sprinkler system because we have 3 separate fire hardened internal staircases, but we did have to add sprinklers to the garage and a fire detection and announcement system to each floor to comply with the new law.
As to vessels... The FAA normally does requires older airliners to comply with new safety regulations. The only flexibility is about the timeframe to make the upgrade.