Because when I do that at my sister in laws home I have to listen to a lecture about how consuming too much salt is bad for your health.
In my own home I noted that even if I feel that I could use a pinch of salt in something other guests do not ask for it but when I do put it , they will too.
Oh yes I have also noted at other people’s home during a dawat nobody , inluding me is the first one to ask for salt. Only at some friends home where I am the only guest and we are very" bay takkaluf" friends I will dare to ask for salt if there will be need for it.