I think we need to keep in mind, that many fake poor quality products, imported into the U.K, have CE stamped on them at the factory/packing stage.
Especially the fakes.
I'm pretty sure - that on many poor quality/fake, mass-imported flexi's, wras/wras I.D can easily be stamped on them too.
Whats left is to, first - develop insight on how to examine a pipe & gage quality, then second - ensure you are buying from a supplier that controls its supply chains - and is likely to have done due diligence.
Surely there is someone out there that can teach us what to look for when examining these staple plumbing parts?