Corrugated flexible drain piping

I’ve been marking flexible drain pipe as temporary plumbing recommend further inspection and repair in my report. The plumber has just advised a homeowner that it is flexible piping, not temporary piping. My understanding is that all drain piping is supposed to be solid and smooth. Interested in other professional opinions

Why this?
Why not recommend installing the correct type of pipe / drain.
Yes I recommend changing but it’s just a note in the report.

No further inspection needed.

Recommend replacement.

I agree.
And no Plumber would say it is okay, he may be one of those all around repair guys not quite qualified but almost, take advantage of opportunity to try and politely educate him

It’s shame there’s no decent search facility for this board…

Here’s an old reference for an authoritative source to back up your comments.

And don’t advise further inspection or evaluation of things that you have already determined are improper. Why invite a contrary opinion?

The bigger question is why does every hardware and plumbing supply store sell flexible drain pipe when it’s not supposed to be used.

You can also buy pre packaged S traps??? Call them out, tell why and move on. If sometbing sells the store could care less if it is proper or works.