If someone owns the building and does not like the idea of toxins in their potable water or are concerned about critters chewing thought the toxic materials that could be a reason and wants a material with over 5,000 years of proven quality and reliability then possibly that's "WHY"
The main thing is YOU SAVE MONEY and forget the motto "plumbers protect the health of the nation"
MONEY over lives is a great idea especially when children are exposed to questionable materials
"Potential chemical leaching is another downside of PEX piping. Due to its chemical composition, the PEX pipe
material may leach toxic chemicals including bisphenol (BPA), MTBE, tertiary butyl alcohol (TBA), and others.Sep 26, 2018"
PEX failures
"Its major failures is
linked to piping and fitting. Piping fails when the pipes are exposed to chlorine that is within the water, exposure to direct sunlight before its installation. Furthermore PEX pipe is vulnerable when it comes in contact with such solutions as petroleum products and oxygen"
https://www.purdue.edu/newsroom/rel...ndards-caused-by-green-building-plumbing.html
I testified against a plastic failure on a waster supply and the case was possibly one of the easiest I ever had to win .
All I did was look at one picture and did not go to the job site. I sent in a one paragraph about the inherent dangers of "plastics" and was paid $2,500
https://www.plasticexpert.com/pex-failures/