We recently ran across this company, Best Access Doors, and had a chance to look over some of their products. One that jumped out at us is their Secret Access Door for Tiling.
It’s a simple access door, with hinge and welded aluminum frame, that’s designed to build into your wall. Then you can apply the tiles to the door, and the surrounding frame. There is a 1/16th inch space around the door, so using a dark grout would probably help conceal the door.
This type of door isn’t needed everywhere, but it’s nice to have this base option to build from when it is needed.