For very low skilled jobs, automation can do the job better than a poor quality worker, because it is predictable and consistent. For jobs that still can't be automated, many of them can be done remotely, and are now done in lower labor cost countries by ambitious, conscientious workers. Jobs that can't be done remotely are being filled by illegal immigrants who are also ambitious, conscientious workers.
If you are at the bottom of the American labor heap, you have never faced competition from machines, globalization, and immigration like you have now. The problem is not just that the alternatives to low-end domestic labor are cheaper, but that they are higher quality, and therefore push the price of low quality domestic labor to near zero.
In the long-term, as machines become able to do more jobs better than humans, people will simply not be willing to pay any price for an error-prone human to do a worse job than a cheap machine. Then, low skilled humans will only be employed in jobs that can only be performed by humans, such as prostitution.