It was definitely called “gravy” in Monmouth County, NJ, and the Philly area. (It makes me mental, but that’s what they called it.)
Here’s your definitive argument. In cooking, there are five “mother” (or “grand”)sauces, classified by Antonin Careme in the 1800s. This is universally accepted and can be easily verified by a simple internet search. They are:
Bechamel
Veloute
Espagnole (or Brown)
Hollandaise
Tomato
Some also include Mayonnaise and Vinagrette in the list.
Now, it could be argued that tomato sauce becomes gravy once you add meat to the mix. The spaghetti sauce that I make incorporates the drippings from searing the meat and the meat juices that collect on the warming plate. However, that’s just splitting hairs. Calling it “gravy” is a regional usage, which makes it correct for that area, but not for the rest of the sauce-eating world.
Small town north of Philadelphia here with a large Italian population. Local Italians say “noodles and gravy” not “spaghetti and sauce.”