What if I turn my back to the player serving? I obviously cannot see contact and thus the serve should be called a fault. This is ridiculous but that is the way the rules are written. The rules need to be changed along the lines of "contact visible from both net posts" and not based on where the player is.
visible from both net posts will be difficult, especially if you serving on the right (like in doubles).
however, there is a free hand be free of the netpost in the umpires handbook.
but imo it is not possible to judge from where the umpires are sitting
10.5 Visibility
10.5.1 The primary requirement of the current service law is for the server to ensure that the
receiver can see the ball throughout the service, and the umpire or assistant umpire must
be satisfied that this is the case. The umpire or assistant umpire should look to see that the
ball is not hidden from the receiver at any stage by any part of the body, or anything he or
she or his or her doubles partner is wearing or carrying, and that the server’s free arm,
which includes the free hand, is not in the space between the ball and the net, once the ball
has been projected upwards.
10.5.2 The ball must be above the level of the playing surface at the start of service. There is,
however, no specific requirement for the receiver to be able to see the racket throughout
service, and the server may quite legitimately begin service with the racket concealed, for
example, behind his or her back.
10.5.3 From their positions in line with the net, especially in case of one umpire per table in the
qualification stage, it may be impractical for the umpire and/or the assistant umpire to judge
whether the ball is struck illegally if it is struck close to the end line or beside a player’s
body. It is, however, the responsibility of the player to serve so that the correctness of his
or her service action can be seen and if he or she serves near the margins of illegality, he
or she runs the risk of being penalised
given that we are in 2025 and nearly 2026, it is so much easier to just put a camera in the dead center of the net, and looking at the players to determine hidden or not.