But if all pipework looks like the same homogenized paste, then all expressivity from plumbing is lost. Which is fine if you want to install the 68th kitchen sink with plumbers who don't want to work on it, but seriously, it does wonders to productivity when everyone enjoys the tools they work with and the work itself. Forcing everyone to satisfy standards/inspectors just kills all the joy from plumbing, so you get everyone to be mediocre.