Well, sorta - in some markets labels can also just be fake (or even in regulated markets I’m sure there can be “mistakes”), but in a lot of them the tags are just describing one (main) fabric.

So a plain shirt made from 100% cotton can be stitched together with a plastic thread. Or have elastic collar (ie plastic).
(Not to mention that you basically can’t get any data on die method used. Or exact fabric characteristics, like thread length. Or weave type. Etc.)

I’m most comfortable if the tag lists like 5 separate 100% items (eg ingredients of the main fabric, of the pocket liners, of buttons, of elastic bits, etc).

Everything is designed to fatigue you out & monetise your actions the most.

But with a lot of clothing you just can’t get non-plastic bits at all - like winter clothes, footwear, etc.

Even more depressive most/all such items have some pfas outer layer (like a teflon or teflon-like coating so it’s more hydrophobic/oleophobic & the water & dirt slides off). But we all breathe it in & it just stays there.

… and then there are ppl who worship clothes made from 100% artificial materials bcs they are “high tech” & have “good performance”.