Except not every database was designed from the ground up to BE a file, that's one of Sqlite's benefits. A database is by definition a single, fully self-contained file. Unless you go out of your way to make Postgres, MySQL, MariaDb, etc. do this, that is very much not the case.

For SQLite, "copying files", rolling file backups, shadow volumes etc. are by definition valid strategies when it comes to SQLite.

Postgres lets you write directly to block. In practice, nobody does this though.