The phenomenon going on here reminds me a little of what happens in BDSM communities. While I personally don't understand the appeal of that kind of sexual escapade, I also understand the logic of it -
In normal, daily life, people must be polite and respectful to each other. For some people (there's a strong trend for this in CEOs/powerful executives who are in a position of power), this creates a strange imbalance and a need to, for once in their life, be the ones being dominated. So these people may walk in the door of a room of a dominatrix, and once they sign a contract, they're beaten, abused... but this abuse is exactly what they signed up for and, perversely, they enjoy it.
I imagine the doorway of this restaurant is a little like that contract - a respite from the obligatory courtesies of daily life.
In normal, daily life, people must be polite and respectful to each other. For some people (there's a strong trend for this in CEOs/powerful executives who are in a position of power), this creates a strange imbalance and a need to, for once in their life, be the ones being dominated. So these people may walk in the door of a room of a dominatrix, and once they sign a contract, they're beaten, abused... but this abuse is exactly what they signed up for and, perversely, they enjoy it.
I imagine the doorway of this restaurant is a little like that contract - a respite from the obligatory courtesies of daily life.