You seem to be looking at the full OOB, not at in-game examples.
The Strength dialog doesn't go below company size for most units, or even Wing/Group size for air units. This means you don't see the units you're actually using in the Strength dialog.
In-game, air units usually show up as a flight or a combined flight of sorts of 2, 4, or 8 aircraft. In Kursk, you're mostly seeing 3, 6 and 9 aircraft units.