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.
Portability and stability. Same as any canned good.
Hell, some things are better canned because once the process is done, it’s essentially exactly where you want it and stays there. Cranberry jelly, tomatoes, pineapple for deserts (seriously, it can be much better than fresh for some applications), peaches for some uses, even corn can be better at some things because it’s canned. There’s others, but it would get silly.
Now, I tend to agree that this isn’t something I would stock up on, what with fresh being relatively easy to get if I was unable to make my own. But, if I lived by myself? If it was decent, it might be a better choice just because it’s a smaller batch size. Less chance of wasting resource.