The Koran says they should use an odd number of stones (best) but they can use any object they find on the ground. Maybe this bidet bum washing is a newer tradition, a result of complaints by Muslims that the "believer" in front of them had ka-ka matted in his butt hairs, or skid marks. Or perhaps the bidet is needed for students to clean up after private lessons from the Imam, how about to clean up AFTER prayers? all that prostrating, especially if they have the flu Is know to cause anal discharge, and according to one hadith, little nuggets left on the mosk floor.
Like...other muslims?