[jasode]

>Why do you think robots would not be able to do those tasks?

The manufacturing of the robots themselves also requires input from unpleasant jobs. The raw materials like steel, plastics, batteries, etc to make the robot. Example of not-so-fun jobs like mining cobalt being done by children: https://www.google.com/search?q=child+labor+cobalt+mines+ev+...

Why can't we have "master" robots build the the "slave" robots? Still the same issue... How do the master robots get built/maintained/repaired?

You also have Moravec's Paradox when trying to build robots that can replace humans' sensory-motor skills (e.g. cleaning sewers, mining cobalt, etc) : https://en.wikipedia.org/wiki/Moravec%27s_paradox

The Boston Dynamics prototype robots have impressive demos of them dancing and jumping but they're probably several decades away from being cost-effective in replacing humans for mining and other unpleasant jobs.