From a quick google, PEX plumbing is not "strictly superior" because it does have some disadvantages compared to copper: https://smartchoice.plumbing/pex-plumb

From a quick google, PEX plumbing is not "strictly superior" because it does have some disadvantages compared to copper: https://smartchoice.plumbing/pex-plumbing-disadvantages-what-you-need-to-know/ https://smartchoice.plumbing/pex-plumbing-disadvantages-what... (I think your overall point is a good one though.)