I believe that this is the Ladenburg in question (there are always several German towns with the same name) and it sounds like a great place to visit. I believe that, when you have a busy restaurant like that, it means the food is pretty good. No wonder the royals tried to get something to eat.
Royalty is somewhat more accepted in Germany since there are princes and princesses and royals living all throughout the country. Should they get preferential treatment? Of course not.