Even if you don’t want to make it, I’ve never been in a supermarket that doesn’t offer a fresher option. I’ve even been in gas stations that offer what they at least claim is fresh potato salad.
Maybe if you really, really wanted potato salad and you were in a food desert but the corner 7-11 has canned potato salad you might buy it, but I’ve never seen this before in my life.
I don’t get it.
I can easily see how something like canned potato salad could be convenient to someone who doesn’t want to spend time cooking and/or doesn’t plan their meals much. Some people buy fresh produce or foods that will last just a couple of weeks in the fridge, they don’t eat it, they throw it away. If you are like this, and only eat potato a couple times a year then you can just stock up on a few cans and not deal with the fresh option which needs planning. You can freeze fresh salad you say? Yes, but sometimes you don’t want to deal with the thawing.
In short this serves the same purpose as canned beans or any other canned meal.