Nice condition Trimo 12" wrench. I always called this smooth, parallel jaw wrenches "monkey" wrenches, but every site I go to call it a "pipe wrench". Handle looks like a pipe wrench but I always thought pipe wrenches had teeth in jaws and a pivoting moveable jaw for pipe. I have even found auto and Ford wrenches called pipe wrenches! What is the story?

The story is that many don't know the difference! If there are no teeth, it won't work on pipe. You are correct in your definitions, though it doesn't HAVE to have a pivoting jaw. Alligator wrenches were used as pipe wrenches in the old days.

Lost history, confused terminology - not the only place it happens*.  Walk into well-equipped garages and ask the owners what water pump pliers are, and how they're used; even a lot of people old enough to know better won't know what you're talking about.

*For a somewhat indirect example, my wife has gotten tired of me rising from my chair and ranting every time a newspaper story talks about the civil rights movement as if the Rev. Dr. Martin Luther King started it his own self - ignoring 150 years of history that preceded King, and, in particular, the years of work by people, some remembered in the histories but some not - during and after World War II that he built on.  This is not to belittle King - he was one of the heroes of the civil rights movement - but he was neither the first nor the only one.

The story is ignorance, and lack of enough interest to find out.  Every single day I look at the offerings on eBay there are several IDs that make me grit my teeth.  I bought a blacksmith's hot cut that was advertised as a mortise ax.  Today there was a 28 inch draw knife advertised as "old farm tool."  A knife that long is a mast knife, and I don't think a lot of old farms were making wind-jambers.  There was very recently a pair of anvil pruners advertised as rare old tongs for stripping wire or some such.   And a riveting hammer called a "Vintage Double Sided Chipping Hammer," and another listed as a farrier's hammer.