You're referencing groups of people that are themselves spread across different groups, not a single individual or single group at the beginning of your "essential" clause that can't be doctors, computer programmers, scientists, and engineers?". The use of the word " who" is more appropriate if you were to be referencing an individual or an individual group. The use of the word "who" as opposed to "that" would be totally inappropriate.
1. First, let's see if doctors, computer scientists, scientists, and engineers can solve all the world's problems without help. 2. There are 1.2 billion people in developed countries. 3. There are 5.9 billion people in undeveloped countries. 4. 774 million people cannot read. 5. 66% of the illiterate people are females. 6. 80% of the American people did not even buy one book this year. 7. Republicans don't even admit we have environmental problems, so they don't believe scientists. 8. Not many people like to work with sick people. There is a shortage of doctors in many places, even here in the US. 9. If you have no people who use computers, why do you need computer programmers. There will be no one to make computers or use them. 10. Dumb people need schools to learn. They need doctors to treat them. They need scientists to invent technology to care for them. They need engineers to build roads, bridges, and provide electricity, etc. 11. Dumb people vote and elect leaders to lead them. They work to care for their families, so they do help solve world problems. 12. It would be dumb to sterilize all the people who aren't doctors, computer programmers, scientists, or engineers.
We still need back-hoe operators, electricians, masons, carpenters (including one Jewish one that we REALLY need right now), auto mechanics, waitstaff . . . all manner of skilled, semi-skilled and unskilled labor. Please don't consider those people to be "dumb" either. They may be happier and more productive than those staffing the trades that you mention in your question.
And don't forget that we need the "welfare" class to justify a big chunk of all the government jobs, so there's that too.
This post was edited by Salt and Red Pepper at November 6, 2016 12:45 PM MST
They get a job at Amazon fulfillment and watch the robots package items for shipment. If the robot gets confused the employee goes over to assist it. The last few things I received were probably prepared by robots. One piece of tape on a huge box................crooked I might add. The box had come opened.
Randy D 