Agreed %100. A tank being able to shoot down a fighter with its main gun in AH is a travesty.
I disagree, we all know it's possible, and not terribly difficult to do...
...If you fly the dumbest attack approach possible.
No one is twisting your arm to fly that low, no one is forcing you to fly at something with a dangerous pointy end that is very easily avoidable.
Other than a random happenstance you are not going to get hit by a tank shell unless you are flying crazy low on a direct strafing approach against one.
So it is not a travesty, it's crappy tactics and flying that causes this. Have a little patience, and set up an attack that keeps you out of danger.
The very good IL2 HurriD pilots make attacks from 45degrees or possibly steeper for a couple of reasons.
1. the attack is made upon the top armor of the target that is usually by far the weakest.
2. The enemy tank can not return fire from it's main gun, because it does not traverse that high.
3. They spent the extra few seconds to set up a proper attack, which maximizes their results, and minimizes their risks. (other than lawndarting)