It probably only works in Japan where, if possible, the toilet is in it's own separate room, separate from the room where you wash your face, separate from the room with the shower/bath. You'd never be in the toilet room except to use the toilet. The door stays closed so the toilet is only going to open when you open the door to the toilet room.
It's still kind of annoying since you can just leave the lid open instead of waiting for it to open...
Except, the motorized seat is indeed convenient, for which the lid might be a dependency, and I guess at which point a scope creep into auto opening everything is just an inevitability.
