If that was truly the case, then why do bombers fly so damn high they might as well be flying offline? .
What means "so damn high" in this context?
Most bombers in this game do things I'd call tactical work (attack on bases) and generally come in at an altitude up to 15k. (Many prever to stay below the first wind layer starting at 14k) Which in my book is not that dam high at all, and ensures that you are quite probably being attacked by fighters. Some do fly higher, though, but generally at or around 20k only.
25k+ Raiders are quite rare in all forms of base centered combat, they are only prevalent in long distance strat runs.
When I go buff hunting at peak hours near very large battles (which tend to increase the combat altitudes), 20k is more than enough to be higher than like 9 out of 10 bombers that come along. In most cases, much higher.
For the record, the average bomber sortie duration for bombers is less than 20 minutes... you don't get very high in that time. And only about one in three bombers gets home to land his mission.