Hydro,
If they get that listing, I would think that they would need a "grounding layer" on top of the 120 V like they do for the under carpet style. You would need something to trip a breaker if they were to stick a nail or thumbtack into the wire.
As for seeing the "tape/wire", I would think that in the right light you would still see a tiny bump on the wall where the tape runs. I mean can't you see the sheet rock tape in the corner, if the drywall mud isn't applied thick enough.
