Certainly, the historic justification for volumetric measuring is likely what you say, that scales were not a thing for most anyone to have until recently. My point was just that recipes used across generations in a family weren't back then (compared to nowadays) likely subject to geographic changes because people were much less likely to move far. I've got nuclear family members on both US coasts and I'm in a landlocked state. That kind of intra-family dispersal is much more common today.