I would say that there are several reasons for this…
I don’t believe that Gaijin has physically tested the penetration of all calibers in the game, both aircraft, tanks and ships, it is probably based on some documents from the past…
I think that 7.7 mm machine guns at a distance of 300 meters are quite adequate, but the other larger calibers are a question of balancing the game…
Another thing is the mouse aiming/3rd person view/markers, the plane is very stable, it can be kept in continuous horizontal flight for a long time, there is a great overview of the flight situation, plus it is significantly more maneuverable…
If you have it, try to try the joystick in ARB, not only do you hit almost nothing through the 3rd person view, you have to get into the cockpit and then just a small movement of the target to the side and you have it outside the sight, so you have to fly at the target aircraft completely differently…
With the joystick, which is to some extent a real stick, you need to have a lot of experience to have more shots in one battle, it is often very good when there is one clean kill and some assistance and that’s how it was probably in real life too…
The bomber damage model is very simplified and at the beginning of the game they were quite durable, but then it happened that players explored the entire tech tree with them, I remember a discussion with one player who opened more than half of the Russian aviation tech tree with the Tu-2…
So this is also a matter of game balancing…
It is generally proven that the fuselage of a bomber aircraft was able to absorb a lot of hits, so real fighters tried (if possible at that speed) to aim at the engines, wings and the wing space between the engines, where the fuel tanks are (fire + explosion = wing break-off), this was also modeled in the game, but those bombers fell to the ground even faster …
Of course you can have a “golden hit” when you hit the tail control, but this control was soon doubled in real life too and that too it wasn’t easy…
Fighters were the ones who decided air battles and that’s what Gaijin is trying to do in the game… The only problem is that the bomber (except for the US big boxes for daytime raids on the Third Reich) benefited not so much from its onboard weapons, but from its invisibility until the last moment, night raids in bad weather when using the first radio-electronic systems for targeting bombs…
The damage model is not the biggest problem, I see the problem in enemy markers, clear and sunny weather in battles and balanced shooting of the onboard gunners (shooting range, shooting timing, etc.)
I’m sending a picture from the analysis of damage to four-engine bombers based on the result in 1942.
In movies (e.g. Battle Of Britain, Lords of the Skies, etc. ) is a relatively realistic depiction of a fighter attack on a bomber - an attack from an altitude and at a relatively high speed, after firing, escape to the sides or upwards, a long stay of the fighter at 6 o’clock is a road to hell…