I don't think I've ever owned a mattress that wouldn't have sagged too much if carried like that, unless maybe I was going to carry out overhead to keep it off the ground. You must be buying much stiffer mattresses than me.

In fairness, I've not moved my current mattress (a memory foam mattress), so maybe that one would work? It's a bit more rigid. But of course no handles at all.

Edit: Nevermind. You're going to turn the mattress on it's side when you actually carry it, and then it will be rigid enough. Handles on the ends work fine for this case, just not the nonexistent case where someone inexplicably tries to carry the mattress flat for more than a few feet.