I've noticed it doesn't count my hits when I shoot trees while RTB.
It does not count when I shoot barns or windmills.
Maybe it is a glitch.
At the risk of stating the obvious, I'm going to take you seriously...
"It"
does count those... As misses... So shooting those, whether you hit them or not,
hurts your hit%.
The good news, though, is that it sounds like you can hit the broad side of a barn, and you don't even need to be inside it to do it, hehe!
If you're in fighter mode, every bullet that fails to connect with an enemy aircraft counts as a miss. Even if it hits "something". GV's, PT boats, buildings, all are misses, even if you hit/destroy them.
In attack mode, you'll get credit for hitting GV's, boats, buildings, ack guns, etc... Shooting trees, barns, windmills will still count as misses.