Scenario 1: the alien craft are piloted by teenagers and stolen from their parents to go on joyrides. Scenario 2: the aliens are bumbling and incompetent, and

Scenario 1: the alien craft are piloted by teenagers and stolen from their parents to go on joyrides. Scenario 2: the aliens are bumbling and incompetent, and stole their spacecraft tech from some more intelligent race. (You could call them "pacleds")