Now normal wall tiles are great, these are real soft and easy to cut with the old angle grinder, so lets say we are in your bathroom, the wall on the right has a 3 cm dip in the middle, the wall on the left is perfectly straight, now a 3 cm dip over a 4 meter span is quite a lot, ie the left and the right aint gonna match up, yet the customer will blame the tiler, should the tiler re render the walls to get them straight? yes he could but then we are talking about a differant price range, you just got him in to tile the bathroom not foking rebuild it.