What I did was ...:
I've put a carpet onto a trapdoor to hide it, then created some redstone signal that opened the trapdoor below the carpet.
What I expected to happen was...:
Fall through the carpet as soon as the trapdoor opened.
What actually happened was...:
I kept standing on the carpet.
Steps to Reproduce:
Obviously.
Why would you assume you could fall through a carpet. Carpets IRL you don't fall through. A thin layer of Snow on the other hand you can both ingame in IRL.