Ketchup enhances most things.....

If a steak is so bad that you need to A-1 or Heinz 57 on it, ketchup ain't going to hurt it either.
You should also reconsider ordering a steak from that place in the future.
As for hot dogs and corn dogs, ketchup and onions! Actually, I'm from Cincinnati, so if a hot dog is what's for lunch, then I prefer Skyline, onions and cheese.
You folks can keep the mustard. I can't stand the taste of it.
As for fries, I prefer BBQ sauce. I also like tarter sauce with fries too. It's the same as mayo, just with the addition of the sweet pickle relish it.
But I learned in the Army, ketchup will make an otherwise horrible meal edible.