Only that with shower trays the joint is not "standing in water" because it is positioned higher. In tiled shower areas, water sometimes stands at these joints (at the rear joint near the drain it probably always does).
With the shower tray, only the water running down the wall "stands" there. The actual water does not stand at these joints.
So worst case the joint cracks. What is supposed to happen then? Behind it is a sealing tape 5-10cm up the wall and a double layer of sealing slurry. The water does not get through by a single millimeter. Even if you don't repair the joint, absolutely nothing should happen. Of course, the joint should be redone.
Concerns from my point of view completely unfounded..
Only that with shower trays the joint does not "stand in water" because it is higher. With tiled shower floors, water sometimes stands on these joints (probably always on the rear joint where the drain is).
With the shower tray, only the water that runs down the wall "stands." The actual water does not stand on these joints.
I had already asked above. What is your solution/alternative for that, which elsewhere is not seen as a problem?