I can’t really think of any food I would use ketchup for but kids love it. There are huge taste and texture variations between the store brands and Heinz, French, Hunts. I get what my kids like and what is on sale.
On the other hand, I put yellow mustard on a lot of things and I eat it straight while I’m working. I buy generic because it’s mostly all the same to me. Other types of mustard vary.