Earlier quoted context omitted.
Never heard of modern teriyaki. How does it differ from the teriyaki that is everywhere in Japan?
The very short version, as I understand it, is that the sauce is different. From interviews I’ve seen of the guy in Seattle who invented it, who came from Japan, he materially changed the sauce primarily to make it much cheaper and easier to produce so that it could be used as an inexpensive, mass market food. Ironically, my understanding is that the Seattle version flowed back to Japan and became common there. His m…
So, as far as the sources I found go, it seems there's Japanese teriyaki, which is a cooking technique, and there's teriyaki sauce, a pre-made sauce developed in the US by Kikkoman, and they are different things, still to this day. The sauce is also sold in Japan nowadays.