Is Adaptive Taxation worthless in a system that only has asteroids?
It supposedly generates 2$ per person on planets... Do Asteroids count as planets for this purpose?
Everything counts as a "planet"; perhaps a better name would have been "outpost" or "colony", except those are already technical terms for systems involving Influence and Approval.
Additionally, these bonuses stack, so if a bonus is +2 of a resource on planets and +1 on, say, arid, any person on an arid planet would be worth +3, which is why planetary exploitation is an important choice.