OK.. here's another way that I MIGHT accept random failures.
Game feature: Strat targets: factories
At the start of the war, all manufacturing and reliabilty are at 100% and no random failures occur.
If the fuel factory is bombed, then a random factor could be induced which "MIGHT" effect the octane level in available fuel, which in turn could limit total output power to an aircraft.
If the ammo factory is bombed, then a random factor could be incuded which "MIGHT" effect ammunition causing a gun to jam, or a bomb ending up being a dud.
If the maintenance hangers on a particular field are damaged, this "MIGHT" cause aircraft leaving that field to have a "POSSIBILITY" of a failure due to poor maintenance.
----
Random failures based on historical data and put into the game "just because" is not something that makes sense. Most of these historical failures (like the P-51B gun jams, Typhoon's poor engine performance at high altitude, etc.) were designed out in updated models.
Failures due to poor manufacturing conditions, low quality materials, untrained aircrews and other factors should not be designed into the game as a simple random thing. Tie these things directly to a strat system that works in the game, and the vague randomness becomes more acceptable (at least to me)
In playing a game/sim, we should be able to assume that the aircraft we choose to fly will work as advertised, unless there is some measurable detraction, such as broken supply lines, factories that are out of commission, airfields that are heavily damaged, etc.
In the real war, pilots had to deal with "random" failures becuase they really had no other choice. But if you think about it, most failures could be attributed to something else.
Like your car, for example... You can drive it and drive it, and if properly maintained, it will last a LONG time with very little chance of failure.
Now, go without maintenance.
1. Oil doesn't get changed because you don't have any fresh oil
2. Radiator hoses don't get replaced because you don't have any new ones.
3. Tires don't get rotated or replaced because your too busy to get it done.
Driving the car now, you have increased the chances of failure. The engine might seize, it might not. The radiator hose might crack, it might not. A tire might go flat or blow out, or it might not. One thing for sure, you CHANCE of failure is increased, but it's not really random when it DOES happen, just WHEN is the randomness.
Anyway, as I said, if we can have a measureable and trackable factor for determining the chances of a failure, it might be better, even for gameplay. It would encourage putting in the extra effort to kill the enemy's refinery, or spare parts factory (please make this new factory HT)
Random failure for history's sake does not a fun game make.