In the end, the laws against insider are simply extensions of the condition that any firm demands from employees and contractors - ie, don't take our take stuff, don't take our delivery van for a joy and don't trade our stock based on secrets we give or leave lying around, ie, The information belongs to the company or its agents and given out to be used for particular purpose.

If there weren't laws against people taking their employer's or contractee's stuff, employers would be hire hit squads to prevent it from happening. Despite vision of libertarian utopias, that wouldn't be an improvement.