What about Salisbury Steak or other cuts that need extensive work to be consumable? One could argue mechanical processes allow lower quality meat to be used as a primary source (for some)?

I don't really buy the idea that mechanical processes = the Processed Food that I was thinking of. But I do think some sins can be hidden in ways a household would never try.

As a layman I'd say that's not wrong: consider the difference between whole oats and finely ground porridge: the latter is bound to taste sweeter and digestion does not have to break down as many chunks, so the body has to do less work.

Hamburger combines meat from many animals. This increases risk of mad cow disease, and makes it riskier to undercook the meat in general.

Different, lower “quality” parts of the animal are used.

Also, because the meat has risks, it is often treated with preservatives.