In the photo you will see a ditra shower base kit, kerdi membrane in the walls, ditra floor membrane and plenty of thinset to adhere it to the floor and walls. This is a lot of labour to install and doubled the amount of thinset you need, like everything it is all up in price. This material is the best to make sure you have tiles that stay on and you don’t get moisture damage. It is also the first thing to cut when the builder needs to shave a few dollars. Plenty of builders are reducing the quality of the work beneath the tiles. In my view it isn’t worth being cheap when the tile and labour already costs a lot. You can’t rely on grout and silicon to make a shower watertight. I can only imagine how bad some of the houses will perform in the future when these cut corners come back to haunt someone.