It’s probably not better, but useful for preppers in an emergency situation; and probably without many additives found in canned food.
Now that you mention it I often use flour & bacon grease for the roux & canned Evaporated Milk; that about as “prepper” as you can get. If I can get fresh milk or half and half of course that’s better.
But Evaporated Milk makes a fine base sausage gravy, or a kind of Béchamel. Just about any fat will work, butter is excellent, beef fat, etc.