STEVE RITCHIE: There was an unwritten law that stated whoever came up with an idea or device got to use it first, but after that it was fair game for any designer at Williams to use the idea or device subsequently. If one of us drew something, then we would talk about it, as it was documented and clear as to who the originator was.

(interview ca. 2010)

How innovations became standards.

Right. I remember Steve Ritchie talking about how in the late 70s/early 80s, any game that deviated too much from the two lower flipper/inlane standard structure would fail commercially, therefore that became a standard.
So you have only a few shots from there. Then any upper flippers are going to have a shot in a rather standard place. Ergo, SR's orbit-to-loop shot that's been reused by SR and other designers since.

All this said, I really don't get the Tron->FH thing much. It plays and flows more like a SR game to me, if anything, than FH or other Lawlor bash toy games. If the upper flipper was on the right side rather than left, we would say it's more like Getaway, I'd suppose.