Look it up anywhere: everyone describes Sears catalog homes as pre-fabricated. So your categorical insistence is contradicted by actual usage. If that makes you uncomfortable for whatever reason, feel free to use whatever term you like, so long as, on actual matters of substance, we understand that we’re talking about homes where some significant portion of the construction is done off site.
Yes, strong agree! Medium density is also the most affordable to build per square footage, compared to low density detached single family homes and high density super tall glass and metal towers.