MechJeb doesn't do proper roll, pitch, gravity turn launches either. It does a pre-programmed ascent profile. In reality all the control of a space launch take

MechJeb doesn't do proper roll, pitch, gravity turn launches either. It does a pre-programmed ascent profile. In reality all the control of a space launch takes place in the first seconds when the vehicle is subsonic. After that it's just pointing to the direction of travel because any angle of attack in the atmosphere would cause excess aerodynamic stress. That's why launch controllers say "nominal" that often. There's nothing that can be done, just hoping that the vehicle stays within the planned bounds. All the accumulated errors from atmospheric conditions and other randomness are corrected by the second stage burn once outside the atmosphere.