Tiler hasnt used aquapanel joint tape

[Scottyb1984]

Hi. Hope everyone is well.
I am after some advice after a tiler started my bathroom yesterday. I told him twice about the aquapanel joint tape and after getting home from work, I noticed he hasn't used it!!
How important is this?
My instinct is to have the tiles off and him start again

 

[Notts_Rob_66]

You might just start by asking him why he hasn’t done as you’d instructed