I grew up in N.H. next to Vt. and don't think I ever heard subs called grinders, not until many years later when I dated someone who grew up in Conn.
That kind of sandwich seems to vary a LOT from one region in the U.S. to another, both in name and what it consists of. I spent a couple years in the PNW in my mid-20s, and couldn't find a decent sub for anything.
Sadly, a lot of the really good mom & pop shops are long gone with only chains left.
Works the other way too, the few companies whose call centers are in the U.S. seem to locate them in the south. Depending on which agent you get, lotsa luck understanding what they're saying and/or getting a resolution to your issue if you're in another part of the country. Do they intentionally hire people with the heaviest regional/ethnic accents they can find?