The only planet ranked is Earth, sitting at the bottom D-tier with a "Taxes" label slapped on it. The joke's brilliance is in what's missing - all other planets are unranked because no human has actually visited them. Technically accurate "hands-on experience" since we've only physically set foot on our own disappointing tax-collecting rock. The empty S, A, B, and C tiers suggest the creator would prefer literally any other planet in our solar system if they could just avoid filing their 1040-EZ form.