The hot dog joint in the town I grew up, didn’t even have ketchup the whole time I lived there. They were hard core. It wasn’t until fries hit the menu that ketchup found it’s way into the restaurant.
Although, some people guess that they got the frier so that they could make fries so that they could have an excuse to have ketchup in the restaurant so that the long time hot dog joint’s aficianados wouldn’t revolt.
Incidentally, the place originated as a hot dog stand in 1886. Ketchup has been in the restaurant, because of the fries, for only about the last ten maybe fifteen years or so.

Even to this day, it’s not uncommone to see the ketchup users look around to see who’s looking (or rather to make sure no one is looking) before putting ketchup on their dog!