No laboratory is required for warships. A laboratory is needed to create and research: a heavy bomber, a heavy tank, a battleship and a railway gun.
Plus, you missed a lot of important units. For example, chemical weapons. It works great and has several secret functions that make it a powerful unit regardless of its level.
In this game, there are only a few "extra" units, which are rarely used by anyone. Otherwise, the player must have all the necessary units for the normal conduct of hostilities.
what secret functions?