Of the fifty or sixty DMD games I purchased probably on ten percent had the latest Roms.
Even machines close to the final production run were still be shipped with early Roms even though updated Roms were available even before the machines left the factories. We're the Roms in those days more important for home owners or operators. Hard to say.
Changing various games over to the latest Roms, sometimes three or four updates later, made a huge difference with dot matrix and gameplay n scoring.
Updating Roms is the first thing to do on any second hand game.
Updating code on any Stern is also a definate must do for obvious reasons.
Maybe it was cheaper for the manufacturers back in the day to post them out to operators than to muck around pulling Roms off brand new boards and stuffing around burning the updates on new ones??