Yendor, an insect riding on a bullet wouldn't be able to see the rotation if the Earth. If you were in a car going 50 miles per hour and you shoot a gun facing backwards then the bullet will be traveling 50 miles per hour slower then normal relative to the ground, and if you shoot it forwards then it will be going 50 miles per hour faster then normal relative to the ground. Relative to the car though the bullet's speed is normal in both instances Simelarly, shooting a gun east and west are the same as far as the bullet's speed goes. It will hit a target to the east with the same speed as a target to the west.
You clearly don't understand the Coriolis effect, the effect is caused because the bullet travels on (more or less) a strait line, while you and the Earth are rotating slowly. This causes the bullet to spear to curve up or down a tiny bit. It isn't really curving, it just appears to be because you and the Earth are rotating. If you want I could give you some videos that explain this concept really well. I know that bullets don't really travel in a strait line, they drop due to gravity and are effected by the air. The Coriolis effect does still noticeably effect the bullet so it needs to be accounted for even though it's not the only factor to account for.
Bullets and airplanes differ in two key ways in this case.
Firstly, airplanes don't generally account for the Coriolis effect because they do not need their trajectory to be precise as that of a bullet, planes have a large margin of error in their flight path while bullets need to be within an inch or so if their intended path.
Secondly, airplanes are controlled by a pilot, while a bullet cannot control it's self in flight. When shooting a bullet you have to come up with it's trajectory and account for all forces acting on it before you fire because after you fire there is nothing you can do to change the bullet's trajectory. Airplanes on the other hand can correct for whatever causes them to deviate from their flight path. If an airplane starts slowly pitching down then the pilot simply pulls up and sets trim to compensate, it doesn't matter if this pitch is caused by the Coriolis effect, the shifting of weight on the plane, turbulence, or a mythical creature messing with the aerodynamics. The plane can adapt to it's situation while a bullet can not.