But tankers and transports are inherently aerodynamically stable.  So if there is a computer error, the default behavior of the plane will be to mostly just fly level-ish.  Fighter jets are designed to be unstable, or at least very close to unstable.  This makes them hella maneuverable, but at the same time, if the computer conks out, then the behavior of the plane will be to keep pitching up or down, and can quickly result in a crash.