You are right, I live in a region where eating is the aim of living (rather than a need to live). Yet when the meat is fresh enough restaurants usually don't offer egg on top (or as an opt-in thing). I would not ask tartare to a non-specialist restaurant, mostly because my taste is wasted by the habit of quality... so I order the things the restaurant do well rather than my favorit dish. And I don't do tartare myself...

So, the egg isn't wrong, but I join you to the fact that if the tartare is good without egg, there is no point to add one (raw beef don't miss protein). And if the egg is needed, I would prefere order something else...