I dont know about restaurants, but in a plant or factory setting, you need to wear a beard net and hairnet so that hair and SKIN doesnt fall into the product. Also, we use magnetic pens just in case they get dropped and need to be fished out with a strkng magnet.

Is it some kind of a joke? LOl, I am afraid the HR would find it difficult to hire only bald people.

Yes, the question is a provoking one for bald people. Some of them may say that they want a hairnet, so as to hide the barron skull. Some may say that they like to be seen as they are. Some may even say that wearing a hairnet without hair is the violation of their human rights.