Stainless steel brained from crawl to shower

See the photo’s, I could not locate anything that says you can or cannot run braided stainless steel supply lines through the floor behind the wall to the shower fixtures. Does anyone one know of a reference that says you can or cannot use them for this purpose?

My understanding is they should be used in exposed or accessible locations. Not sealed up in the wall as done in this house.

What are your opinions on this? There are other considerations in the pictures that required an eval I’m aware of.

Thank you in advance.

amateur plumbing observed at water supply to … bath shower . I recommend repairs by a qualified plumbing contractor…nuff said…

^ Yep. I would report as amateurish plumbing… daisy chained supply risers used os as piping…