I have flown countless online maps and I can honestly say i have only ever been hit by flak once, a bofors somthing or other caused a minor leak on my 110.
Not sure if that was luck or aimed. I know from experience in il2 that a lot of flak can be very resource hungry (server/bandwidth)
My guess is it may have been dialed down by the developers in a hurry to get the game out the door.
Expect it to hit you right between the eyes in a patch or two's time
