Pepper is best when fresh, and its an easy way for them to provide an experience for diners where they feel like someone is giving them special care when it comes to their food, if that makes sense. Salt makes no difference freshly ground. Also, at least in the USA, generally no one will be insulted if you ask for salt; is that an experience you have often? And do you have to ask for salt often? Anywhere I eat they just have salt shakers available, it seems odd to me that they'd make people ask