If it were really true that replacing backhoe operators with shovels would improve employment, then why wouldn't we go further and replace shovels with spoons? The fact is that employers face competition for employees in a free market just as much as job seekers face competition for jobs. Wages are bid down AND up, so what ultimately determines wages is productivity. Backhoe operators are so much more productive than manual ditch diggers that society can afford to pay the manufacturers and servicers of backhoes, manufacturers of the parts , the miners and harvesters of raw materials and the suppliers of fuel substantially more than the unskilled laborers they displace.
I'm sorry, but if you are too stupid or stubborn to upgrade your skills when technology makes them obsolete, it's your problem-not society's.
You cannot convince a starving person to die quietly when society leaves him behind, that he doesn't deserve to live because he is 'not good enough'. shit is going to get ugly under this model. no matter the perceived level of skill a person needs, the vast majority will always be relatively stupid.
and why should we leave them behind, there is more wealth in the world than ever before!
.......unless you want to argue that we need to self propagate. that is a sad truth.