If no one does dirty jobs, their price goes up until it's worthwhile for someone to do them (think of Uber surge). Basic supply and demand.
More costly dirty jobs encourage automation and they will be automated away. The trend has started long ago. It used to take 3 people per garbage truck to collect trash, one driver and 2 people physically pick up the trash cans. Then it was 2 as better trucks came along. Now it's one driver per truck, as the truck has mechanical arms to collect the trash.
With driverless trucks in the horizon, it is not far fetch to have one driver overseeing 2 to a small fleet driverless trucks to collect garbage on a street in parallel.