But then you're comparing apples an oranges: meat is low in sodium in its unprocessed form, but so are all the ingredients of the plant-based alternative before adding salt.

What matters is not so much the natural form, it is how the product is typically consumed.

But of course I see your point that with home made meat-based patties, you are in control of how much salt you want to add, while with factory made patties, you have to take what you get, it's typically not possible to "take away" salt. Mind you, though, the latter argument holds for both plant-based and meat-based factory-made patties.