why do ppl have anuses

theyre clearly not useful and only vestigial organs.
without anus, waste would just go thru the colon and the sphinctre and outside
no anus necessary
dogs dont have anuses
why do humans when were supposed to be more evolved?

We would not need an anus if our metabolisms were designed as a closed loop.  Waste products would merely require energy inputs in order to be processed back into metabolic materials.  In effect, we would be internally connected ass-to-mouth forever.