I don't know about middle east, but yes, those are common in europe. Because washing with water is cleaner than wiping with paper after a #2. If there is a showerhead next to the toilet, as in the picture, it's called a douche. If there is a separate toilet bowl looking thing, it's a bidet. You probably seen those before. I think they are just too messy, so I like the japanese way where there is a automatic water wash system build into the toilet. I have been using them for years now and love it. Toto has one called Washlet. Kohler has the Numi and Duravit has the sensowash. They are more common now and a lot more brands carry them, even costco has them.(not by toto or duravit).. If you want one, Toto is probably the best..

More about this drain, It installs easily, has its pros cons. I like that it sets flat on subfloor and gets screwed in ( this could be done in slab too). The green Protective tape is heavy duty and great up until you have to tear it off to do this. The cons being the clamping flange and screws( which BTW is why i used this drain). The flange itself has over 20 screw holes, They are not beveled out and the screws when snugged tite set a good 1/16th above flange and dont seat well. the flange itself needed a good de-burring. It gets the job done and clamps tightly. I went ahead and used some membrane on top of the screws and under my tile edge as a sleep well measure. At nearly 3/4 the cost of a good stainless drain id say its benefit is the clamping flange, even if its lacking. It plays nice with the USG durock shower system and I was able to get both of my MFG reps support using the 2 together (another reason i chose this drain).

The 'premium', as they call it, is a better material with more choices in size and color. The pan is treated as any other pan/base with the tiled walls coming down over the edges. I'm having the walls tiled, just don't want tile on the floor. The preformed bases are made with a slope and a drain location of the end, center or a grate-type drain along one end. Here is an example.

Did you mistype the shower size, or is it really 6'x5'? I would be surprised if you can find a prefabricated acrylic tray that is that big. Most would max out at about 5'x3' unless you get into expensive specialty products. The Schluter Kerdi shower trays are widely used and the products are well respected. It should not be hard to find a tile installer that is familiar with the product and knows how to do a proper installation. I don't know about Wedi products, but you can always ask your contractor. Bruce